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  • Articles  (2,166)
  • Escherichia coli
  • Industrial Chemistry and Chemical Engineering
  • Wiley-Blackwell  (1,686)
  • Springer  (463)
  • Nature Publishing Group (NPG)  (14)
  • FISON  (3)
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  • Articles  (2,166)
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  • 1
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    Bacteriological assessment of smoked fish (Clarias Sp.) around Shiroro Lake area of Niger State, Nigeria (2021)
    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24185 | 19325 | 2018-05-16 14:41:02 | 24185 | Fisheries Society of Nigeria
    Details
    Publication Date: 2021-07-15
    Description: Bacteria has been implicated in food poisoning, and smoked fish is not an exception.Generally, fish is highly susceptible to spoilage; therefore this study evaluated the bacteria load in smoked fish from three major locations in Shiroro area of Niger State namely; Gwada, Kuta and Zumba.The smoked fish samples collected from these locations were smeared at both the gills and head regions of the fishes. The bacteria samples identified were Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermis, Pseudomonas aeruginosa, and Samonella typhi, which were common to all the three locations sampled, while only Streptococcus feacaliswas only was found to be present in both Kuta and Zumba location.The frequency of occurrence of these 68 bacteria samples isolated ranges from 8 - 20%, with Bacillius subtilis having the highest occurrence and Pseudomonas aeruginosa have the least occurrence. Out of the total 68 samples, 14 skin samples (20.6%) and 5 gills samples (7.4%) exceeded the acceptable limits of total mesophilic aerobic counts which were 10〈sup〉6〈/sup〉 - 10〈sup〉7〈/sup〉 cfu/g. In the case of total coliform counts, 12 skin samples (17.6%) and 7 gills samples (10.3%) exceeded the acceptable limit which is 4.0 x 102, while in the case of Staphylococcus aureus, 4 skin samples (5.9%) and 2 gills samples (2.9%) exceeded the acceptable limit which is 103 cfu/g. Similarly 3 skin samples (4.4%) and 1 gill sample (1.5%) exceeded the acceptable limit of Salmonella typhi which is 104 cfu/g.
    Description: Includes: 4 tables.;Also includes: 21 references.
    Keywords: Fisheries ; Health ; Escherichia coli ; Bacillus subtilis ; Staphylococcus aureus ; Staphylococcus epidermis ; Pseeudomonas aeruginosa ; Nigeria ; Shiroro L. ; Bacteria ; Smoked (Clarias spp) fish ; Location and recommended values ; brackishwater environment ; freshwater environment ; marine environment ; Bacteria ; Food poisoning ; Cured products ; Fish ; Fish spoilage ; Acceptability ; Lake fisheries ; Gills ; Brain ; Evaluation
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 140-144
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  • 2
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    Microbiological quality of fresh tilapia raised in ponds fertilized with raw and sterilized cow dung manures (2021)
    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24222 | 19325 | 2018-05-19 07:06:04 | 24222 | Fisheries Society of Nigeria
    Details
    Publication Date: 2021-07-15
    Description: A total of 2,800 tilapia (Oreochromis niloticus) were stocked in seven duplicates 5 by 4 m2 earthen ponds in NIFFR Integrated Farm, New-Bussa, Niger-State. Raw and sterilized poultry manure of 0.13 to 0.52 kg/m3 concentrations were used to fertilize the ponds with the unfertilized ponds serving as control. The following bacteria were isolated from the cow dung manure; Escherichia coli, E. co1iOl57:H7, Aeromonas hydrophila,Salmonella typhi, Shigella dysenteriae and Staphylococcus aureus. The fish samples from the 0.13 and 0.26 kg/m3 sterilized manure fertilized ponds had zero count in the muscles while samples from other ponds had pathogens in their fish muscles. The study revealed that fish samples from sterilized manures were better in terms of microbial safety for fish productions hence sterilized manure are recommended for use in fish production to ensure the microbial safety of the fish, handlers and that of the consumers.
    Description: includes: 13 references.
    Keywords: Aquaculture ; Oreochromis niloticus ; Escherichia coli ; Aeromonas hydrophila ; Samonela typhi ; Shigella dysenteriae ; Staphylococcus aureus ; Nigeria ; Niger State ; Catfish ; Pathogens ; Microbial quality ; Raw and sterilized manue ; freshwater environment ; Bacteria ; Freshwater fish ; Fish culture ; Fish ponds ; Manure ; Microorganisms ; Freshwater aquaculture ; Aquaculture products ; Food fish ; Quality assurance ; Muscles ; Microbial contamination
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 278-280
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  • 3
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    Assessment of the bacteriological profile of water and fish samples from Hadejia reservoir in Jigawa State (2021)
    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24609 | 19325 | 2018-05-22 05:56:26 | 24609 | Fisheries Society of Nigeria
    Details
    Publication Date: 2021-07-15
    Description: Hadejia reservoir is a floodplain complex in north eastern Nigeria. This area has long been noted for its importance in fish production. It is also important to both year round native birds and European water birds that travel over the Sahara desert to this wetland to spend their winters. Quantitatiive and qualitative profile of bacteria in the reservoir was carried out. Quantitative analysis of bacteria in the water revealed that the water contained total heterotrophic count (THC) of 3.1 x 103 CFU/ml to 3.5 x 106 cfu/ml and total coliform count (TCC) ranging from 1.4 x 102 to 1.4 x 103 CFU/ml. Bacteria load in the fish intestines were 3.5 x 103 CFU/g and 3.1 x 104 CFU/g for total coliform and total heterotrophic count respectively. Fish gills had less count (2.1 x 102 CFU/g and 3.4 x 102 CFU/g for TCC and THC respectively), than the fish intestines. Bacteria species such as Aeromonas hydrophila, Vibrio cholera, Shigella species were isolated from the water samples. Escherichia coli, Salmonella sp. Shigella sp. were isolated from the fish samples.
    Description: Includes: 12 references.
    Keywords: Ecology ; Fisheries ; Aeromonas hydrophila ; Vibrio cholera ; Escherichia coli ; Nigeria ; Hadejia Reservoir ; Bacteriological profile ; Hadejia reservoir ; freshwater environment ; automation
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 167-170
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  • 4
    Electronic Resource
    Electronic Resource
    Thermal inducible expression of xylose isomerase and its performance in a hollow fiber bioreactor (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 1-5 
    Details
    ISSN: 1476-5535
    Keywords: Xylose isomerase ; Enzyme expression ; thermally inducible ; Hollow fiber bioreactor ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary TheEscherichia coli xylose isomerase (EC 5.3.1.5) has been expressed under the control of a thermal inverting promotor system (att-nutL-p-att-N block) and its performance in a hollow fiber bioreactor measured. The conversion of xylose to xylulose was inversely proportional to the flow rate and the system operated up to 60°C. The maximum conversion efficiency observed was 19.05% at 55°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569686
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  • 5
    Electronic Resource
    Electronic Resource
    Evaluation of the growth of microorganisms on diaper absorbent materials (1988)
    Springer
    Journal of industrial microbiology and biotechnology 3 (1988), S. 21-28 
    Details
    ISSN: 1476-5535
    Keywords: Diaper ; Staphylococcus aureus ; Escherichia coli ; Candida albicans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Methods were developed to study the effects of absorbent materials from diapers on microbial survival, growth and toxic shock syndrome toxin-1 (TSST-1) production under specified in vitro conditions. Growth of representative skin and fecal flora organisms was equivalent in cultures in which materials from cotton cloth diapers, disposable diapers or disposable diapers containing absorbent gelling material were added as the sole carbon source. In urine used as an enrichment medium, growth of the test organisms in media containing material from the three diaper types was equivalent and no contribution to growth from the diaper material was detected. TSST-1 was not produced byStaphylococcus aureus under conditions in which urine was added to the diaper materials. Pathogenic strains of organisms purposefully introduced onto diapers failed to survive and the few microbial cells normally found in diaper material did not multiply when stored under conditions favorable to microbial growth. The data indicate that all three diaper types tested were the same with respect to growth and survival of representative skin and fecal organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569438
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  • 6
    Electronic Resource
    Electronic Resource
    Isolation and some properties of lysineN 6-hydroxylase fromEscherichia coli strain EN222 (1989)
    Springer
    BioMetals 2 (1989), S. 1-5 
    Details
    ISSN: 1572-8773
    Keywords: LysineN 6-hydroxylase ; External flavoprotein (FAD) monooxygenase ; Aerobactin ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Lysine N6-hydroxylase was isolated as a soluble enzyme from the supernatant after ultrasonication ofEscherichia coli strain EN222 which contained the structural gene on a multicopy plasmid (as described by Engelbrecht and Braun in 1986). The apoenzyme prepared by dialysis was purified by ammonium sulfate precipitation and fast protein liquid chromatography using Superose 12 and Mono Q columns. The molecular mass as determined by gel filtration was 200 kDa and 50 kDa by SDS/polyacrylamide gel electrophoresis. The enzyme binds 0.79 molecule FAD/50 kDa. The activity of the enzyme is strictly dependent on NADPH. Its properties are similar to other flavoprotein monooxygenases of the EC group 1.14.13.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01116193
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  • 7
    Electronic Resource
    Electronic Resource
    Mobilization ofEscherichia coli R1 silver-resistance plasmid pJT1 by Tn5-Mob intoEscherichia coli C600 (1990)
    Springer
    BioMetals 3 (1990), S. 24-27 
    Details
    ISSN: 1572-8773
    Keywords: Silver-resistance-accumulation ; Escherichia coli ; Mobilization ; Tn5-Mob ; Plasmid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Escherichia coli Rl is an Ag+-resistant strain that, as we have shown recently, harbours at least two large plasmids, pJT1 (83 kb) and pJT2 (77 kb). Tn5-Mob was introduced into theE. coli Rl host replicon via conjugation on membrane filters. The transfer functions of plasmid RP4-4 were provided in this process and Tn5-Mob clones mated withE. coli C600 yielded Ag+-resistant transconjugants. This mobilization procedure allowed transfer and expression of pJT1 Ag+ resistance inE. coli C600. Prior to use of Tn5-Mob mobilization, it was not possible to transfer Ag+-resistant determinant(s) intoE. coli by conjugation or transformation including high-voltage electroporation.E. coli C600 containing PJTI and PJT2 displayed decreased accumulation of Ag+ similar toE. coli R1.E. coli C600 could not tolerate 0.1 and 0.5 mM Ag+, rapidly accumulated Ag+ and became non-viable. Tn5-Mob mobilization may be useful in the study of metal resistance in bacteria, especially in strains not studied for resistance mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01141173
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  • 8
    Electronic Resource
    Electronic Resource
    Transport of iron across the outer membrane (1991)
    Springer
    BioMetals 4 (1991), S. 14-22 
    Details
    ISSN: 1572-8773
    Keywords: Iron ; Outer membrane ; Escherichia coli ; TonB ; FhuA ; Colicin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The TonB protein is involved in energy-coupled receptor-dependent transport processes across the outer membrane. The TonB protein is anchored in the cytoplasmic membrane but exposed to the periplasmic space. To fulfill its function, it has to couple the energy-providing metabolism in the cytoplasmic membrane with regulation of outer membrane receptor activity. Ferrichrome and albomycin transport, uptake of colicin M, and infection by the phages T1 andϕ80 occur via the same receptor, the FhuA protein in the outer membrane. Therefore, this receptor is particularly suitable for the study of energy-coupled TonB-dependent transport across the outer membrane. Ferrichrome, albomycin and colicin M bind to the FhuA receptor but are not released into the periplasmic space of unenergized cells, ortonB mutants. In vivo interaction between FhuA and TonB is suggested by the restoration of activity of inactive FhuA proteins, bearing amino acid replacements in the TonB box, by TonB derivatives with single amino acid substitutions. Point mutations in thefhuA gene are suppressed by point mutations in thetonB gene. In addition, naturally occurring degradation of the TonB protein and its derivatives is preferentially prevented in vivo by FhuA and FhuA derivatives where functional interaction takes place. It is proposed that in the energized state, TonB induces a conformation in FhuA which leads to the release of the FhuA-bound compounds into the periplasmic space. Activation of FhuA by TonB depends on the ExbBD proteins in the cytoplasmic membrane. They can be partially replaced by the TolQR proteins which show strong sequence similarity to the ExbBD proteins. A physical interaction of these proteins with the TonB protein is suggested by TonB stabilization through ExbB and TolQR. We propose a permanent or reversible complex in the cytoplasmic membrane composed of the TonB protein and the ExbBD/TolQR proteins through which TonB is energized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01135552
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  • 9
    Electronic Resource
    Electronic Resource
    HPLC separation of enterobactin and linear 2,3-dihydroxybenzoylserine derivatives: a study on mutants ofEscherichia coli defective in regulation (fur), esterase (fes) and transport (fepA) (1994)
    Springer
    BioMetals 7 (1994), S. 149-154 
    Details
    ISSN: 1572-8773
    Keywords: 2,3-dihydroxybenzoylserine ; enterobactin ; Escherichia coli ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Reversed-phase HPLC separation of enterobactin and its 2,3-dihydroxybenzoylserine derivatives was used for a comparative analysis of mutants of Escherichia coli, defective in the regulation of enterobactin biosynthesis (fur), enterobactin transport (fepA) and enterobactin esterase (fes). A complete separation of all 2,3-dihydroxybenzoylserine compounds was achieved: the monomer (DHBS), the linear dimer (DHBS)2 and trimer (DHBS)3, the cyclic trimer, enterobactin, as well as 2,3-dihydroxybenzoic acid. The production of all these compounds was followed after ethylacetate extraction from acidified culture fluids. Enterobactin was found to be the predominant product in all mutant strains. The mutant strains behaved differently with regard to the breakdown products. All degradation products, such as DHBS, (DHBS)2 and (DHBS)3, were detected in the overproducing fur mutant where both transport and esterase are still functioning, while only the monomer, DHBS, was detected in the fepA mutant and no degradation was found in the esterase-deficient fes mutant. From the pattern of breakdown products it may be inferred that the esterase acts in two different ways, depending on whether transport is functioning or not. Thus, esterolytic cleavage of ferric enterobactin after entering the cells results in a mixture of all three hydrolysis products, i.e. DHBS, (DHBS)2 and (DHBS)3, while cleavage of iron-free enterobactin subsequent to its biosynthesis yields only the monomer. Thus, the results of quantitative HPLC analysis of enterobactin and its breakdown products show that different enterobactin esterase products arise, depending on whether iron is bound to enterobactin or not.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00140485
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  • 10
    Electronic Resource
    Electronic Resource
    Enhanced production of poly(3-hydroxybutyrate) by filamentation-suppressed recombinantEscherichia coli in a defined medium (1996)
    Springer
    Journal of polymers and the environment 4 (1996), S. 131-134 
    Details
    ISSN: 1572-8900
    Keywords: Escherichia coli ; poly(3-hydroxybutyrate) (PHB) ; filamentation ; fed-batch culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Fed-batch cultures of recombinantEscherichia coli strains were carried out for the production of poly(3-hydroxybutyric acid) (PHB) in a chemically defined medium. TheE. coli strains used were XL1-Blue, harboring pSYL105, a stable high-copy number plasmid containing theAlcaligenes eutrophus polyhydroxyalkanoate (PHA) genes, and XL1-Blue, harboring pSYL107, which is pSYL105 containing theE. coli ftsZ gene to suppress filamentation. With XL1-Blue(pSYL105) the final cell mass and PHB concentration obtained in 62 h were 102 and 22.5 g/L, respectively. Fed-batch culture of XL1-Blue(pSYL107) under identical conditions resulted in a final cell mass and PHB concentration of 127.5 and 48.2 g/L, respectively. The PHB contents obtained with XL1-Blue(pSYL105) and XL1-Blue(pSYL107) were 22.1 and 37.8%, respectively. Therefore, PHB was more efficiently produced in a defined medium by employing filamentation-suppressed recombinantE. coli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02074874
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  • 11
    Electronic Resource
    Electronic Resource
    Effect of complex nitrogen source on the synthesis and accumulation of poly(3-hydroxybutyric acid) by recombinantEscherichia coli in flask and fed-batch cultures (1994)
    Springer
    Journal of polymers and the environment 2 (1994), S. 169-176 
    Details
    ISSN: 1572-8900
    Keywords: Escherichia coli ; poly(3-hydroxybutyric acid) ; defined medium ; complex nitrogen source ; fed-batch culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract When a recombinantEscherichia coli XL1-Blue harboring pSYL105 was cultured in a complex medium, a poly(3-hydroxybutyric acid) (PHB) concentration of 7.16 g/L was obtained in 48 h. However, a PHB concentration of only 0.91 g/L was obtained in 60 h by culturing in a defined medium. Also, fed-batch culture in a defined medium resulted in considerably lower PHB accumulation than in a complex medium. With the aim to produce a high concentration of PHB at a reduced medium cost, we examined 10 complex nitrogen sources for their ability to promote PHB synthesis in a defined medium. Tryptone, casamino acids, and casein hydrolysate promoted PHB synthesis to a higher extent than the others tested. PHB synthesis was also enhanced during fedbatch cultures when a defined medium was supplemented with various complex nitrogen sources. With tryptone supplementation a PHB concentration of 66.7 g/L could be obtained in 44 h. Yeast extract was less effective for promoting PHB synthesis than tryptone. Corn steep liquor, which did not enhance PHB synthesis significantly, could promote PHB synthesis considerably when supplemented together with yeast extract in both flask and fed-batch cultures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02067442
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  • 12
    Electronic Resource
    Electronic Resource
    Development of DNA probes for cytotoxin and enterotoxin genes in enteric bacteria (1988)
    Springer
    Cellular and molecular life sciences 44 (1988), S. 848-853 
    Details
    ISSN: 1420-9071
    Keywords: DNA probes ; cytotoxin and enterotoxin genes ; Escherichia coli ; Shigella spp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary DNA probes to identify the genes encoding toxins in enteric bacteria have been developed. Use of these probes reduces the number of animals required for toxicity testing, as suspect bacteria can be directly tested for the presence of toxin. We have augmented the gene probes available by developing probes against theEscherichia coli enterotoxin LTII and shiga toxin fromShigella dysenteriae 1. The LTII gene fromE. coli 357900 was identified and characterised and a suitable internal probe was obtained. The LTII gene was found not to be common among enterobacteriae from various geographical locations. Isolates predominately of animal origin from Nigeria and Thailand hybridized with the probe. The shiga toxin gene was isolated fromS. dysenteriae 1 by a combination of in vivo and in vitro methods. An internal probe was identified and used against different serogroups ofShigella andE. coli isolated. The probe was found to hybridize withS. dysenteriae 1 isolates and also someS. flexneri andS. sonnei strains. Representatives were tested for toxin production and found to produce toxin at low levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01941182
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  • 13
    Electronic Resource
    Electronic Resource
    Synthesis and activity of p-azidobenzoyloxyferricrocin, a photoactivatable analog of ferrichrome (1999)
    Springer
    BioMetals 12 (1999), S. 151-160 
    Details
    ISSN: 1572-8773
    Keywords: photoaffinity labeling ; Escherichia coli ; FhuA ; siderophores ; ferrichrome ; azidobenzoyldesferriferricrocin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract p-azidobenzoyloxy desferriferricrocin (AF) 2, a photoactivatable analog of ferrichrome, was prepared by selective acylation of the serine group of ferricrocin 1 in two steps: transesterification of ferricrocin followed by demetallation. A model compound, (L) 2-benzyloxycarbonylamino-3-p-azidobenzoyloxy N-isopropyl propionamide 8, was separately synthesized in order to set up optimal transesterification conditions to avoid α, β-elimination or epimerization of serine. Binding of iron-loaded AF (FeAF) to the FhuA outer membrane receptor protein of Escherichia coli AB2847 was demonstrated by inhibition of ferrichrome transport, interference with the infection by the bacteriophage φ80 and with killing of cells by albomycin and colicin M. FeAF transported iron only weakly which indicates that the photoaffinity moiety is incompatible with transport or intracellular iron release from the siderophore.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009225811420
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  • 14
    Electronic Resource
    Electronic Resource
    DNA sequence analysis of the tellurite-resistance determinant from clinical strain of Escherichia Coli and identification of essential genes (2000)
    Springer
    BioMetals 13 (2000), S. 135-139 
    Details
    ISSN: 1572-8773
    Keywords: Escherichia coli ; heavy metals ; tellurite resistance ; ter genes ; transposon insertion mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The tellurite-resistant Escherichia coli strain KL53 was found during testing of the group of clinical isolates for antibiotics and heavy metal ion resistance (Burian et al. 1990). Determinant of the tellurite resistance of the strain was located on the large conjugative plasmid pTE53 and cloned into pACYC184. Three different Ter clones harboring pLK2, pLK18 and pLK20 were isolated (Burian et al. 1998). The smallest functional Ter clone harboring pLK18 was chosen for further analysis. Plasmid pLK18 have been subcloned to obtain convenient DNA fragments for sequencing of tellurite-resistance determinant. Sequencing of this DNA fragments provided complete DNA sequence of the determinant, 5250 bp in size. The sequence has been compared with nucleotide and protein databank (BLAST programs) and significant homology with the three known operons coding for tellurite resistance has been found (determinat on plasmid pR478 from Serratia marcescens, on plasmid pMER610 from Alcaligenes sp. and chromosomal tellurite resistance genes from Proteus mirabilis). We identified 5 ORFs coding for 5 genes named terB to terF. The clone harboring pLK18 was subjected to the transposition with Tn1737Km to disrupt determinant of the tellurite resistance. Plasmid DNA of several clones containing pLK18 with Tn1737Km was isolated to locate the target site of Tn1737Km. Analyses showed, the genes terB, terC, terD and terE are essential for conservation of the resistance whereas the gene terF is not important in this respect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009272122989
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  • 15
    Electronic Resource
    Electronic Resource
    Diversity of siderophore genes encoding biosynthesis of 2,3-dihydroxybenzoic acid in Aeromonas spp. (1994)
    Springer
    BioMetals 7 (1994), S. 227-236 
    Details
    ISSN: 1572-8773
    Keywords: 2,3-dihydroxybenzoic acid ; Aeromonas spp. ; amonabactin ; enterobactin ; Escherichia coli ; iron acquisition ; siderophore genes ; siderophores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Most species of the genus Aeromonas produce the siderophore amonabactin, although two species produce enterobactin, the siderophore of many enteric bacteria. Both siderophores contain 2,3-dihydroxybenzoic acid (2,3-DHB). Siderophore genes (designated aebC, -E, -B and -A, for aeromonad enterobactin biosynthesis) that complemented mutations in the enterobactin genes of the Escherichia coli 2,3-DHB operon, entCEBA(P15), were cloned from an enterobactin-producing isolate of the Aeromonas spp. Mapping of the aeromonad genes suggested a gene order of aebCEBA, identical to that of the E. coli 2,3-DHB operon. Gene probes for the aeromonad aebCE genes and for amoA (the entC-equivalent gene previously cloned from an amonabactin-producing Aeromonas spp.) did not cross-hybridize. Gene probes for the E. coli 2,3-DHB genes entCEBA did not hybridize with Aeromonas spp. DNA. Therefore, in the genus Aeromonas, 2,3-DHB synthesis is encoded by two distinct gene groups; one (amo) is present in the amonabactin-producers, while the other (aeb) occurs in the enterobactin-producers. Each of these systems differs from (but is functionally related to) the E. coli 2,3-DHB operon. These genes may have diverged from an ancestral group of 2,3-DHB genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149553
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  • 16
    Electronic Resource
    Electronic Resource
    Selenium metabolism in Escherichia coli (1998)
    Springer
    BioMetals 11 (1998), S. 223-227 
    Details
    ISSN: 1572-8773
    Keywords: Escherichia coli ; metabolic rates of selenium ; selenium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Escherichia coli will reduce selenite (SeO 3 2- ) andselenate (SeO 4 2- ) to elemental selenium Se 0 . Seleniumwill also become incorporated intoproteins as part of the amino acids selenocysteine or selenomethionine.The reaction of selenitewith glutathione produces selenodiglutathione (GS-Se-GS). Selenodiglutathioneand itssubsequent reduction to glutathioselenol (GS-SeH) are likely the key intermediatesin the possiblemetabolic fates of selenium. This review presents the possible pathwaysinvolving selenium in E. coli. Identification of intermediates and potentialprocesses from uptake of the toxic oxyanions through to theirdetoxification will assist us inunderstanding the complexities of metalloid oxyanion metabolism in thesebacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009290213301
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  • 17
    Electronic Resource
    Electronic Resource
    Identification of the ferrioxamine B receptor, FoxB, inEscherichia coli K12 (1992)
    Springer
    BioMetals 5 (1992), S. 37-46 
    Details
    ISSN: 1572-8773
    Keywords: Escherichia coli ; ferrioxamine receptor ; iron transport ; photoaffinity label ; siderophores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The photoreactivep-azidobenzoyl analog of ferrioxamine B was used to show that ferrioxamine-B-mediated iron transport is separate and distinct from coprogen-mediated iron transport inEscherichia coli. Photolysis of this analog inhibited uptake of [59Fe]ferrioxamine B but not [59Fe]coprogen or [59Fe]ferrichrome. Conversely, photolysis of thep-azidobenzoyl analog of coprogen B inhibited uptake of [59Fe]coprogen but not [59Fe]ferrioxamine B or [59Fe]ferrichrome. Photolabeling of outer membranes withp-azidobenzoyl-[59Fe]ferrioxamine B resulted in the labeling of two iron-regulated peptides with molecular masses of about 66 and 26 kDa. Expression of these peptides was increased when ferrioxamine B was the sole iron source. Both peptides were present in outer membrane preparations of thefhuF mutant H1717, but the 66 kDa peptide was not inducible. These results are evidence for an outer membrane receptor inE. coli unique for linear ferrioxamines.
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    Selective disadvantage of non-functional protein synthesis inEscherichia coli (1976)
    Springer
    Journal of molecular evolution 8 (1976), S. 317-328 
    Details
    ISSN: 1432-1432
    Keywords: Selection ; Continuous Culture ; Non-Functional Protein Synthesis ; Escherichia coli ; Metabolic Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Comparison of growth rates of isogenic strains that synthesize varying levels ofβ-galactosidase during continuous culture on non-inducing medium indicates that synthesis of low levels of non-functional protein has a small but possibly significant effect upon growth rate.
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    URL: http://dx.doi.org/10.1007/BF01739257
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    The density distribution of gene loci over the genetic map ofEscherichia coli: Its structural, functional and evolutionary implications (1981)
    Springer
    Journal of molecular evolution 17 (1981), S. 354-360 
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    ISSN: 1432-1432
    Keywords: Escherichia coli ; Genetic map ; Gene density ; Genome evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A quantitative analysis was carried out on the dispersion of gene loci over theE. coli genetic map. Therefore, the map was divided into regions characterized by an homogeneous gene density. This created a distribution pattern of gene loci that contained a symmetry axis located near to the origin of DNA replication. The pattern could be subdivided into a set of 22 functional domains containing gene loci whose products revealed a biochemical or functional relatedness. A correlation was found between the boundary positions of these domains and the distribution of F plasmid- and DNA insertion sites over theE. coli chromosome. The structural, functional and evolutionary implications of these findings are discussed.
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    URL: http://dx.doi.org/10.1007/BF01734357
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    Counterselection of GATC sequences in enterobacteriophages by the components of the methyl-directed mismatch repair system (1991)
    Springer
    Journal of molecular evolution 33 (1991), S. 125-132 
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    ISSN: 1432-1432
    Keywords: GATC sequence ; Counterselection ; Mismatch repair system ; Enterobacteriophages ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Weak to severe deficit of GATC sequences in the DNA of enterobacteriophages appears to be correlated with their undermethylation during growth indam + (GATC ade-methylase) bacteria. This observation is corroborated by the sequence analysis showing no evidence for site-specific mutagenicity of 6meAde. The MutH protein of the methyl-directed mismatch repair system recognizes and cleaves the undermethylated GATC sequences in the course of mismatch repair. To enquire whether the MutH function of the methyldirected mismatch repair system participates in counterselection of GATC sequences in enterobacteriophages, we have studied the yield of bacteriophage ϕX174 containing either 0, 1, or 2 GATC sequences, in wild type,dam, andmut (H, L, S, U) Escherichia coli. Following transfection with unmethylated DNA containing two GATC sequences, a net decrease in the yield of infective particles was observed in all bacterialmutH + dam− strains, whereas no detectable decrease was observed in bacteria infected by DNA without GATC sequence. This effect of the MutH function is maximum in wild type andmutL andmutS bacteria whereas the effect is not significant inmutU bacteria, suggesting an interaction of the, helicase II with the MutH protein. However, indam + bacteria, the presence of GATC sequences leads to an increased yield of infective particles. The effect of GATC sequence and its Dam methylation system on phage yield inmutH − bacteria reveals that methylated GATC sequences are advantageous to the phage. These results suggest that the methyl-directed mismatch repair system, and in particular its MutH protein, may have participated in severe counterselection of GATC sequences from enterobacteriophages, presumably, by DNA cleavage or by interfering with DNA replication or packaging when GATC sequences are undermethylated. Coevolution of the Dam and MutH proteins could then account for the loss of GATC sequences from DNA of bacteriophages growing indam + hosts.
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    URL: http://dx.doi.org/10.1007/BF02193626
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    Electrophoretic and immunological comparisons of chloroplast and prokaryotic ribosomal proteins reveal that certain families of large subunit proteins are evolutionarily conserved (1989)
    Springer
    Journal of molecular evolution 29 (1989), S. 68-88 
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    ISSN: 1432-1432
    Keywords: Ribsomal proteins ; Chloroplast ; Two-dimensional gel electrophoresis ; Immunological cross-reactivity ; Protein evolution ; Peptidyltransferase ; Anabaena 7120 ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Antibodies to individual chloroplast ribosomal (r-)proteins ofChlamydomonas reinhardtii synthesized in either the chloroplast or the cytoplasm were used to examine the relatedness ofChlamydomonas r-proteins to r-proteins from the spinach (Spinacia oleracea) chloroplast,Escherichia coli, and the cyanobacteriumAnabaena 7120. In addition,35S-labeled chloroplast r-proteins from large and small subunits ofC. reinhardtii were coelectrophoresed on 2-D gels with unlabeled r-proteins from similar subunits of spinach chloroplasts,E. coli, andAnabaena to compare their size and net charge. Comigrating protein pairs were not always immunologically related, whereas immunologically related r-protein pairs often did not comigrate but differed only slightly in charge and molecular weight. In constrast, when35S-labeled chloroplast r-proteins from large and small subunits of a closely related speciesC. smithii were coelectrophoresed with unlabeledC. reinhardtii chloroplast r-proteins, only one pair of proteins from each subunit showed a net displacement in mobility. Analysis of immunoblots of one-dimensional SDS and two-dimensional urea/SDS gels of large and small subunit r-proteins from these species revealed more antigenic conservation among the four species of large subunit r-proteins than small subunit r-proteins.Anabaena r-proteins showed the greatest immunological similarity toC. reinhardtii chloroplast r-proteins. In general, antisera made against chloroplast-synthesized r-proteins inC. reinhardtii showed much higher levels of cross-reactivity with r-proteins fromAnabaena, spinach, andE. coli than did antisera to cytoplasmically synthesized r-proteins. All spinach r-proteins that cross-reacted with antisera to chloroplast-synthesized r-proteins ofC. reinhardtii are known to be made in the chloroplast (Dorne et al. 1984b). FourE. coli r-proteins encoded by the S10 operon (L2, S3, L16, and L23) were found to be conserved immunologically among the four species. Two of the large subunit r-proteins, L2 and L16, are essential for peptidyltransferase activity. The third (L23) and two otherE. coli large subunit r-proteins (L5 and L27) that have immunological equivalents among the four species are functionally related to but not essential for peptidyltransferase activity.
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    The use of ribonuclease U2 in RNA sequence determination (1974)
    Springer
    Journal of molecular evolution 3 (1974), S. 63-77 
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    ISSN: 1432-1432
    Keywords: 16S Ribosomal RNA ; Oligonucleotide ; Fingerprint ; Ribonuclease U2 ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The catalog of oligomers produced by ribonuclease T1 digestion ofEscherichi coli 16S ribosomal RNA has been determined by a new method that involves the use of ribonuclease U2 fromUstilago sphaerogena. The sequences for the larger T1 oligomers (8 or more bases) determined in this way differ in more than 50 % of the cases from those reported previously (determined by other methods).
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    Procaryote phylogeny (1974)
    Springer
    Journal of molecular evolution 3 (1974), S. 293-299 
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    ISSN: 1432-1432
    Keywords: Phylogeny ; Escherichia coli ; Aerobacter aerogenes ; 16 S Ribosomal RNA ; Oligomer Catalog
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The catalog of oligonucleotides produced by T1 ribonuclease digestion ofAerobacter aerogenes 16 S ribosomal RNA has been determined and compared to that characterizingEscherichia coli. It is concluded that the two 16 SrRNAs are approximately 98% similar, making the organisms very closely related.
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    Characterization of the primary structural homology between the 16 S ribosomal RNAs ofEscherichia coli andBacillus megaterium by oligomer cataloging (1972)
    Springer
    Journal of molecular evolution 1 (1972), S. 230-240 
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    ISSN: 1432-1432
    Keywords: Escherichia coli ; Bacillus megaterium ; Oligomer Catalog ; Molecular Fossil Record ; Two Dimensional Electrophoretogram ; Sequence Homology ; Phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The 16 S ribosomal RNAs of twoProcaryotes, Escherichia coli andBacillus megaterium were characterized by oligomer cataloging (oligomers produced by T1 nuclease digestion), in an attempt to detect their primary structural homology and as an initial step in characterizing this homology. Oligomer sequence coincidence between the two catalogs far in excess of the random expected levels was observed. Statistically significant coincidence was most pronounced for the hexamers and pentamers, suggesting that the overall structure of 16 S ribosomal RNA may be such that conservation of large stretches of its primary structure (e.g. over eight nucleotides in length) is not in general essential.
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    Detection of fundamental principles and a level of order for large-scale gene clustering on the Escherichia coli chromosome (1993)
    Springer
    Journal of molecular evolution 36 (1993), S. 347-360 
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    ISSN: 1432-1432
    Keywords: Chromosome evolution ; Gene evolution ; Bacterial chromosomal expansion ; Chromosomal gene organization ; Gene clustering ; Gene duplication ; Escherichia coli ; Bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Escherichia coli K-12 genetic map was divided into intervals of equal length to count the number of genes per interval. Plots of genes per interval at four sets of interval lengths revealed large-scale clustering of genes with the major clusters occurring at regularly spaced distances apart. Major gene cluster properties were analyzed at a scale of 100 intervals wherein each interval corresponded to a genetic map unit length of 1 min. In any major gene cluster, the highest gene concentration was observed at or near the midpoint interval, and the number of genes per interval was found to decline exponentially as a function of the linear distance from the midpoint or interval of peak gene concentration of that cluster. An autocorrelation analysis of gene content in first-neighbor intervals throughout the chromosome revealed an ordered first-neighbor relationship in comparison to 2,000 randomized interval versions of the chromosome. Attempts to simulate gene placement by a Gaussian model did not produce large-scale gene clustering in any way comparable to that observed on the chromosome. We propose that major gene clusters formed from smaller gene clusters, and the contemporary chromosome formed from fusion of homologous or heterologous major gene clusters.
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    Synonymous substitutions are clustered in enterobacterial genes (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 448-451 
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    ISSN: 1432-1432
    Keywords: Synonymous substitution ; Escherichia coli ; Salmonella typhimurium ; Mutation ; Recombination ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The spatial distribution of synonymous substitutions in enterobacterial genes is investigated. It is shown that synonymous substitutions are significantly clustered in such a way that a synonymous substitution in one codon elevates the rate of synonymous substitution in an adjacent codon by about 10%. The level of clustering does not appear to be related to the level of gene expression, and it is restricted to a range of two or three codons. There are at least three possible explanations: (1) sequence-directed mutagenesis, (2) recombination, and (3) selection.
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    Nucleotide composition and kinetic complexity of the genomic DNA of an intracellular symbiont in the pea aphidAcyrthosiphon pisum (1987)
    Springer
    Journal of molecular evolution 24 (1987), S. 205-211 
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    ISSN: 1432-1432
    Keywords: Endosymbiont ; Aphid ; Genome size ; Nucleotide composition ; Cell organelle ; Mycoplasma ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An intracellular symbiont was isolated from the mycetocyte of the pea aphidAcyrthosiphon pisum, and its genomic DNA was compared with those ofEscherichia coli andMycoplasma capricolum with respect to nucleotide composition and kinetic complexity. Thermal dissociation, CsCl density equilibrium centrifugation, and high-performance liquid chromatography of the nuclease P1 digest all indicated that the G+C content of the endosymbiont DNA is as low as 30%. In this respect, the endosymbiont resembledMycoplasma species. The reassociation kinetics of genomic DNA labeled by nick translation suggested that the endosymbiont genome is 1.4×1010 daltons in size, about 5 and 18 times as large as those ofE. coli andM. capricolum, respectively. The results were confirmed by reassociation of endosymbiont DNA labeled by incubation with [3Hthymidine in Grace's medium. The endosymbiont genome of the aphid was about 500 times larger than those of leafhopper endosymbionts previously analyzed by ultracentrifugation. These characteristic properties of the aphid endosymbiont genome are discussed in connection with the evolution of cell organelles, and with reference to a previous finding that most of the genes of the aphid endosymbiont are not expressed when present intracellularly.
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    Sex in Escherichia coli does not disrupt the clonal structure of the population: evidence from random amplified polymorphic DNA and restriction-fragment-length polymorphism (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 440-448 
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    ISSN: 1432-1432
    Keywords: Escherichia coli ; RAPD ; RFLP ; Clonal theory ; Recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Analysis of the Escherichia coli population by multilocus enzyme electrophoresis (MLEE) has established its clonal organization, but there is increasing evidence that horizontal DNA transfer occurs in E. coli. We have assessed the genetic structure of the species E. coli and determined the extent to which recombination can affect the clonal structure of bacteria. A panel of 72 E. coli strains from the ECOR collection was characterized by random amplified polymorphic DNA (RAPD) and restriction-fragment-length polymorphism (RFLP) of the ribosomal RNA gene (rrn) regions. These strains have been characterized by MLEE and are assumed to reflect the range of genotypic variation in the species as a whole. Statistical analysis, including factorial analysis of correspondence (FAC) and hierarchical classifications, established that the data obtained with the three genetic markers are mutually corroborative, thus providing compelling evidence that horizontal transfer does not disrupt the clonal organization of the population. However, there is a gradient of correlation between the different classifications which ranges from the highly clonal structure of 132 group strains causing extraintestinal infections in humans to the less-stringent structure of B1 group strains that came mainly from nonprimate mammals. This group (B1) appears to be the framework from which the remaining non-A group strains have emerged. These results indicate that RAPD analysis is well suited to intraspecies characterization of E. coli. Lastly, treating the RAPD data by FAC allowed description of subgroup-specific DNA fragments which can be used, in a strategy comparable to positional cloning, to isolate virulence genes.
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    The functional significance of the evolutionary divergence between the tryptophan operons ofEscherichia coli andSalmonella typhimurium (1974)
    Springer
    Journal of molecular evolution 4 (1974), S. 121-137 
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    ISSN: 1432-1432
    Keywords: Tryptophan Biosynthesis ; Escherichia coli ; Salmonella typhimurium ; Genetic Divergence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Hybrid strains ofEscherichia coli andSalmonella typhimurium were constructed in which intergeneric complementation was required for tryptophan biosynthesis. The functional aspects of in vivo tryptophan biosynthesis in these hybrid strains were compared with similar strains ofE. coli. There was little indication that the hybrid strains were deficient in tryptophan biosynthesis as a result of their hybrid nature, although the tryptophan operons of the two species differ by approximately one thousand mutations. It is tentatively concluded that this genetic divergence has not detectably altered the functional properties of the operon and is likely to be the result of accumulation of neutral mutations.
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    The close proximity ofEscherichia coli genes: Consequences for stop codon and synonymous codon use (1996)
    Springer
    Journal of molecular evolution 42 (1996), S. 73-78 
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    ISSN: 1432-1432
    Keywords: Synonymous codons ; Stop codons ; Shine-Dalgarno ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It is shown that synonymous codon usage is less biased in favor of those codons preferred by highly expressed genes at the end ofEscherichia coli genes than in the middle. This appears to be due to the close proximity of manyE. coli genes. It is shown that a substantial number of genes overlap either the Shine-Dalgarno sequence or the coding sequence of the next gene on the chromosome and that the codons that overlap have lower synonymous codon bias than those which do not. It is also shown that there is an increase in the frequency of A-ending codons, and a decrease in the frequency of G-ending codons at the end ofE. coli genes that lie close to another gene. It is suggested that these trends in composition could be associated with selection against the formation of mRNA secondary structure near the start of the next gene on the chromosome. Stop codon use is also affected by the close proximity of genes; many genes are forced to use TGA and TAG stop codons because they terminate either within the Shine-Dalgarno or coding sequence of the next gene on the chromosome. The implications these results have for the evolution of synonymous codon use are discussed.
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    Physiological significance and bioenergetic aspects of glucose dehydrogenase (1989)
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    Antonie van Leeuwenhoek 56 (1989), S. 51-61 
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    ISSN: 1572-9699
    Keywords: glucose dehydrogenase ; bioenergetics ; growth yield ; enzyme regulation ; chemostat culture ; Acinetobacter calcoaceticus ; Klebsiella aerogenes ; Escherichia coli ; Pseudomonas species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The regulation of the PQQ-linked glucose dehydrogenase in different organisms is reviewed. It is concluded that this enzyme functions as an auxiliary energy-generating mechanism, because it is maximally synthesized under conditions of energy stress. It is now definitively established that the oxidation of glucose to gluconate generates metabolically useful energy. The magnitude of the contribution of the oxidation of glucose to gluconate via this enzyme to the growth yield of organisms such asAcinetobacter calcoaceticus is not yet clear.
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    Quantitative aspects of glucose metabolism by Escherichia coli B/r, grown in the presence of pyrroloquinoline quinone (1991)
    Springer
    Antonie van Leeuwenhoek 60 (1991), S. 373-382 
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    ISSN: 1572-9699
    Keywords: glucose metabolism ; Escherichia coli ; pyrroloquinoline quinone ; glucose dehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Escherichia coli B/r was grown in chemostat cultures under various limitations with glucose as carbon source. Since E. coli only synthesized the glucose dehydrogenase (GDH) apo-enzyme and not the appropriate cofactor, pyrroloquinoline quinone (PQQ), no gluconate production could be observed. However, when cell-saturating amounts of PQQ (nmol to μmol range) were pulsed into steady state glucose-excess cultures of E. coli, the organisms responded with an instantaneous formation of gluconate and an increased oxygen consumption rate. This showed that reconstitution of GDH in situ was possible. Hence, in order to examine the influence on glucose metabolism of an active GDH, E. coli was grown aerobically in chemostat cultures under various limitations in the presence of PQQ. It was found that the presence of PQQ indeed had a sizable effect: at pH 5.5 under phosphate- or sulphate- limited conditions more than 60% of the glucose consumed was converted to gluconate, which resulted in steady state gluconate concentrations up to 80 mmol/l. The specific rate of gluconate production (0.3–7.6 mmol·h-1·(g dry wt cells)-1) was dependent on the growth rate and the nature of the limitation. The production rate of other overflow metabolites such as acetate, pyruvate, and 2-oxoglutarate, was only slightly altered in the presence of PQQ. The fact that the cells were now able to use an active GDH apparently did not affect apo-enzyme synthesis.
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    The growth rate control in Escherichia coli at near to maximum growth rates: the A-stat approach (1997)
    Springer
    Antonie van Leeuwenhoek 71 (1997), S. 217-230 
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    ISSN: 1572-9699
    Keywords: Escherichia coli ; specific respiration rate ; stoichiometric growth model ; growth yields ; A-stat ; ATP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth characteristics of Escherichia coli K-12 in the continuous culture with a smooth increase in the dilution rate (A-stat) of various carbon sources (glucose, acetate, succinate, glycerol, lactate, acetate + succinate, casamino, acids + glucose) were studied. For all substrates studied the maximum value of specific respiration rate, Q O2, remained between 14–18 mmol O2 h-1 g dwt-1 and the maximum growth rate varied from 0.22 h-1 on acetate to 0.77 h-1 on glucose + casamino acids. After the respiratory capacity of the cells was exhausted at growth rates µ 〈 µcrit, the growth yield YXO2, increased slightly when the dilution rate increased. The maximum growth rate of Escherichia coli K12 was dependent on growth yield, respiratory capacity and glycolytic capacity of the strain. Analysis of the cultivation data using a stoichiometric flux model indicated that ATP synthesis in E. coli exceeds by two-fold that (theoretically) required to build up biomass. The experimental value of mATP 〈 4 mmol ATP h-1 g dwt-1 determined from A-stat cultivation data was low compared with the calculated ‘unproductive hydrolysis’ of ATP (64–103 mmole ATP g dwt-1).
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    Underexpression of porin protein OmpF in agar-entrapped, sessile-like Escherichia coli (1997)
    Springer
    Antonie van Leeuwenhoek 72 (1997), S. 271-274 
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    ISSN: 1572-9699
    Keywords: antibiotic resistance ; biofilms ; Escherichia coli ; immobilized cells ; outer membrane proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The electrophoretic patterns of the outer membrane proteins of agar-entrapped Escherichia coli cells were found to be different from those of free organisms. In particular, the porin protein OmpF was underexpressed in immobilized bacteria, that displayed enhanced resistance to latamoxef.
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    A comparative study on the frequency of prophages among natural isolates of Salmonella and Escherichia coli with emphasis on generalized transducers (1998)
    Springer
    Antonie van Leeuwenhoek 73 (1998), S. 49-54 
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    ISSN: 1572-9699
    Keywords: Salmonella typhimurium ; Escherichia coli ; bacteriophages ; generalized transduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several collections of natural isolates of the genus Salmonella and of the species Escherichia coli were studied for the release of viable temperate phages. The results indicated that functional prophage genomes may be a common constituent of all bacterial genomes of the investigated strains. About 99% of the Salmonella phages are capable of generalized transduction of chromosomal host markers and plasmids. The ratio of transducing E. coli phages is significantly lower.
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    Genetic engineering of bacteria and their potential for Hg2+ bioremediation (1997)
    Springer
    Biodegradation 8 (1997), S. 97-103 
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    ISSN: 1572-9729
    Keywords: Escherichia coli ; genetic engineering ; mercury bioaccumulation ; mercury transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ion exchange or biosorptive processes for metalremoval generally lack specificity in metal bindingand are sensitive to ambient conditions, e.g. pH,ionic strength and the presence of metal chelators. Inthis study, cells of a genetically engineered Escherichia coli strain, JM109, which expressesmetallothionein and a Hg2+ transport system afterinduction were evaluated for their selectivity forHg2+ accumulation in the presence of sodium,magnesium, or cadmium ions and their sensitivity to pHor the presence of metal chelators during Hg2+bioaccumulation. The genetically engineered E.coli cells in suspension accumulated Hg2+effectively at low concentrations (0-20 µM) overa broad range of pH (3 to 11). The presence of 400 mMsodium chloride, 200 mM magnesium chloride, or100 µM cadmium ions did not have a significanteffect on the bioaccumulation of 5 µm Hg2+,indicating that this process is not sensitive to highionic strength and is highly selective against sodium,magnesium, or cadmium ions. Metal chelators usuallyinterfere with ion exchange or biosorptive processes.However, two common metal chelators, EDTA and citrate,had no significant effect on Hg2+ bioaccumulationby the genetically engineered strain. These resultssuggest that this E. coli strain could be usedfor selective removal of Hg2+ from waste water orfrom contaminated solutions which are resistant tocommon treatments. A second potential applicationwould be to remove Hg2+ from Hg2+-contaminated soil, sediment, or particulates bywashing them with a Hg2+ chelator andregenerating the chelator by passing the solutionthrough a reactor containing the strain.
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    Effects of the virulence plasmid ColV, I-K94 on the sensitivity ofEscherichia coli to putative environmental inhibitory agents (1985)
    Springer
    Cellular and molecular life sciences 41 (1985), S. 133-136 
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    ISSN: 1420-9071
    Keywords: Escherichia coli ; ColV plasmid ; inhibitory agents ; environmental inhibitors, sensitivity to
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Derivatives ofEscherichia coli carrying the virulence plasmid, ColV, I-K94 were more resistant than the ColV− parents to phage Mel but were more sensitive to the hydrophobic inhibitors deoxycholate, erythromycin and lysozyme. The basis for these changes in sensitivity has been examined in ColV+ mutants with altered colicin or VmpA protein levels and in ColV+ strains with repressed transfer properties.
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    Differential sensitivity to tributyltin of cytochrome-containing and cytochrome-deficient cells ofEscherichia coli SASX76 (1985)
    Springer
    Cellular and molecular life sciences 41 (1985), S. 764-766 
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    ISSN: 1420-9071
    Keywords: Escherichia coli ; cytochrome deficiency ; tributyltin ; differential sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of tributyltin (TBT) chloride on the growth of cytochrome-deficient and cytochrome-containing cells ofEscherichia coli SASX76 was examined. The former cells were found to be at least 20 times more sensitive to TBT. It is proposed that the differential sensitivity of these two cell types to the biocide, TBT, may be due to a different mode of energy generation by cytochrome-deficient and cytochrome-sufficient cells. In addition to the energy state, the pH change caused by the presence and absence of cytochromes which occurred during growth also resulted in a differential sensitivity of these cells.
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    Hotspots of homologous recombination (1994)
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    Cellular and molecular life sciences 50 (1994), S. 234-241 
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    ISSN: 1420-9071
    Keywords: Homologous recombination ; hotspots ; nucleases ; meiosis ; Escherichia coli ; Chi ; Schizosaccharomyces pombe ; M26
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Homologous recombination occurs at higher than average frequency at and near hotspots. Hotspots are special nucleotide sequences recognized by proteins that promote, directly or indirectly, a rate limiting step of recombination. This review focuses on two well-studied examples, the Chi sites of the bacteriumEscherichia coli and the M26 site of the fission yeastSchizosaccharomyces pombe. Chi, 5′ G-C-T-G-G-T-G-G 3′, is recognized by the RecBCD enzyme, which nicks the DNA near Chi and produces a 3′-ended single-stranded DNA ‘tail’; this tail is a potent substrate for homologous pairing by RecA and single-stranded DNA binding proteins. M26, 5′ A-T-G-A-C-G-T 3′, is recognized by a heterodimeric protein and stimulates, by an as-yet-unknown mechanism, meiotic recombination at and near theade6 gene. Additional hotspots in bacteria, fungi, and mammals enhance recombination directly or indirectly via a variety of mechanisms. Although hotspots are widespread among organisms, the biological role of their localized enhancement of recombination remains a matter of speculation.
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    The role of exogenous iron in the activation of ribonucleotide reductase from Escherichia coli (1997)
    Springer
    JBIC 2 (1997), S. 418-426 
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    ISSN: 1432-1327
    Keywords: Key words Ribonucleotide reductase ; Iron metabolism ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  Protein R2, the small component of ribonucleotide reductase from Escherichia coli, contains a diferric center and a catalytically essential tyrosyl radical. In vitro, this radical can be produced in the protein from two inactive forms, metR2, containing an intact diiron center and lacking the tyrosyl radical, and apoR2, lacking both iron and the radical. While activation of apoR2 requires only a source of ferrous iron and exposure to O2, activation of metR2 was achieved using a multienzymatic system consisting of an NAD(P)H:flavin oxidoreductase, superoxide dismutase and a poorly defined protein fraction, named fraction b (Fontecave M, Eliasson R, Reichard P (1987) J Biol Chem 262 : 12325–12331). In both reactions, reduced R2, containing a diferrous center, is a key intermediate which is subsequently converted to active R2 during reaction with O2. By in vivo labeling of E. coli with radioactive 59Fe, we show that fraction b contains iron. Depletion of the iron in fraction b inactivates it, and fraction b can be substituted for by ferric citrate solutions. Furthermore, aqueous Fe2+ in the presence of dithiothreitol is able to convert metR2 into reduced R2. Therefore we propose that the function of fraction b is to provide, in association with the flavin reductase, ferrous iron for reduction of the endogenous diiron center. Since fraction b is not a single well-defined protein, it remains to be shown whether, in vivo, that function resides in a specific protein. Exogenous iron can thus participate in activation of both apoR2 and metR2, but it is incorporated into R2 only in the former case. A unifying mechanism is proposed.
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    Biomechanical effects of shock waves onEscherichia coli and λphage DNA (1995)
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    Shock waves 4 (1995), S. 293-297 
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    ISSN: 1432-2153
    Keywords: Biomechanical effect (of shock wave) ; Escherichia coli ; λphage DNA ; Cell destruction ; DNA fragmentation ; Diaphragmless shock tube
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics , Technology
    Notes: Abstract Escherichia coli (recombinant cells) and λphage DNA in suspension liquid were exposed to pressure pulses of about 20μs duration and amplitude of up to 14 MPa. These pulses were generated by a diaphragmless shock tube. The destruction of cells was monitored by the assay of phenylalanine dehydrogenase leaking from the recombinant cells and was found to increase remarkably at the peak pressure of higher than 12 MPa. A probability relation for the cell destruction expressed as a function of pressure was proposed. It is most likely that there exists a threshold pressure for the cell destruction. Fragmentation effects of shock waves on λphage DNA were analyzed by electrophoresis. They were enhanced by increasing the shock wave strength and the number of shots. Probability for the DNA fragmentation as a function of pressure and molecular size was estimated with HPLC. The larger size of the DNA was more easily fragmented. A threshold pressure does not seem to exist for the DNA fragmentation.
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    DNA integration into recipient yeast chromosomes by trans-kingdom conjugation between Escherichia coli and Saccharomyces cerevisiae (1992)
    Springer
    Current genetics 21 (1992), S. 101-108 
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    ISSN: 1432-0983
    Keywords: Trans-kingdom conjugation ; DNA integration ; Saccharomyces cerevisiae ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary IncQ-derived conjugative shuttle vectors, which carried the yeast gene URA3 and/or the yeast autonomously replicating sequence (ARS1), were constructed. Both the ars-plus plasmid pAY205 and the ars-less plasmid pAY201 were successfully transmitted from E. coli to S. cerevisiae by the action of mob and tra. In this trans-kingdom conjugation, plasmid pAY205 could replicate and be retained in transconjugants. Plasmid pAY201 caused the formation of “micro-colonies” of abortive transconjugants due to its transient expression and rapid disappearance. Nevertheless, one per about 103 colonies caused by transmitted pAY201 plasmids were uncurable by integration into the homologous region of a yeast chromosome. Analyses by restriction enzyme mapping and Southern hybridization indicate that this integration is primarily caused by a double crossover during conjugation and not by a single reciprocal recombination.
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    Effect of passage through the intestinal tract of detritivore earthworms (Lumbricus spp.) on the number of selected Gram-negative and total bacteria (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 227-232 
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    ISSN: 1432-0789
    Keywords: Earthworms ; Lumbricus spp. ; Bacterial survival ; Enterobacter cloacae ; Escherichia coli ; Aeromonas hydrophila ; Pseudomonas putida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Laboratory experiments were carried out to investigate the fate of bacteria during and after passage through the intestinal tract of detritivore earthworms. Earthworms (Lumbricus spp.) were fed with cattle dung inoculated 7 days previously with one of five different Gram-negative bacteria. Bacterial concentrations were determined 2 days later in dung and soil, and in gut material from different parts of the earthworm intestinal tract. A high percentage (28–82%) of the total bacteria (epifluorescence direct counts) in the earthworm gut content was culturable. The concentration of total heterotrophic aerobic bacteria did not vary significantly among the five different bacterial additions and the non-inoculated control. In earthworm casts the number of total heterotrophs per gram dry matter (2.1×109) was higher than in soil (1.7×108), but lower than in the dung (1.5×1010). The test-bacteria, however, showed different survival patterns along the earthworm intestinal tract. The concentrations of Escherichia coli BJ 18 and Pseudomonas putida MM 1 and MM 11 in earthworm casts were lower than in the ingested dung, while concentrations of Enterobacter cloacae A 107 and Aeromonas hydrophila DMU 115 in dung and casts were similar. Ent. cloacae, and to aminor extent E. coli, were reduced in numbers by several orders of magnitude in the pharynx and/or crop. In the hind gut, however, the concentration of Ent. cloacae had increased to the same level as in the ingested dung, while the concentration of E. coli remained low. Our observations indicate that the bacterial flora of ingested food materials changes qualitatively and quantitatively during gut transit.
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    A continuous culture study of an ATPase-negative mutant of Escherichia coli (1977)
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    Archives of microbiology 113 (1977), S. 185-189 
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    ISSN: 1432-072X
    Keywords: Continuous culture ; Growth yield ; Escherichia coli ; ATPase ; Oxidative phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract For anaerobic glucose-limited chemostat cultures of Escherichia coli a value of 8.5 was found for Y ATP max . For anaerobic glucose- or ammoniumlimited chemostat cultures of the ATPase-negative mutant M2-6 of E. coli Y ATP max values of 17.6 and 20.0 were found, respectively. From these data it can be concluded that in the wild type during anaerobic growth 51–58% of the total ATP production is used for energetization of the membrane. Using the Y ATP values obtained in the anaerobic experiments a P/O ratio of 1.46 could be calculated for aerobic experiments with the wild type. It is concluded that from the energy obtained by respiration in wild type E. coli about 60% is used for membrane energetization and only about 40% for the actual formation of ATP. No dramatic difference in the maintenance requirement for ATP or glucose has been observed between glucose- and ammonium-limited chemostat cultures of the mutant. The large difference in maintenance requirement observed for such cultures of the wild type is therefore supposed to be made possible by ATP hydrolysis by the ATPase.
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    Effect of guanosine 5′-diphosphate 3′-diphosphate and related nucleoside polyphosphates on induction of tryptophanase and β-galactosidase in permeabilized cells of Escherichia coli (1978)
    Springer
    Archives of microbiology 119 (1978), S. 81-86 
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    ISSN: 1432-072X
    Keywords: Guanosine tetraphosphate ; Adenosine pentaphosphate ; ppGpp ; pppApp ; Nucleoside polyphosphate ; Tryptophanase ; β-Galactosidase ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Exogenous addition of guanosine and adenosine 5′-(mono, di and tri) phosphate 3′-diphosphates (pppGpp, ppGpp, pGpp, pppApp, ppApp and pApp) stimulated the synthesis of tryptophanase and β-galactosidase in permeabilized cells of Escherichia coli. From the results obtained with ppGpp and pppApp, this effect appeared to be at a transcriptional level and depended greatly on the growth condition; the largest effect was observed in cells under shiftdown or grown on poor energy source. ppGpp and pppApp, unlike cyclic AMP, did not act to overcome the inhibition of enzyme induction by glucose, but in combination with cyclic AMP caused a synergistic stimulation effect. In the shiftdown cells, ppGpp and pppApp gave 30% or more stimulation effect on tryptophanase induction while cyclic AMP did not stimulate induction. There was therefore a pronounced difference between cyclic AMP and ppGpp or pppApp in stimulatory function.
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    An Escherichia coli mutant defective in the NAD-dependent succinate semialdehyde dehydrogenase (1982)
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    Archives of microbiology 132 (1982), S. 270-275 
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    ISSN: 1432-072X
    Keywords: Escherichia coli ; Succinate semialdehyde dehydrogenase ; Aromatic catabolism ; Hydroxyphenylacetate ; Genetic mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Escherichia coli mutants, unable to grown on 4-hydroxyphenylacetate, have been isolated and found to be defective in the NAD-dependent succinate semialdehyde dehydrogenase. When the mutants are grown with 4-aminobutyrate as sole nitrogen source an NAD-dependent succinate semialdehyde dehydrogenase seen in the parental strain is absent but, as in the parental strain, an NADP-dependent enzyme is induced. Growth of the mutants is inhibited by 4-hydroxyphenylacetate due to the accumulation of succinate semialdehyde. The mutants are more sensitive to inhibition by exogenous succinate semialdehyde than is the parental strain. Secondary mutants able to grow in the presence of 4-hydroxyphenylacetate but still unable to use it as sole carbon source were defective in early steps of 4-hydroxyphenylacetate catabolism and so did not form succinate semialdehyde from 4-hydroxyphenylacetate. The gene encoding the NAD-dependent succinate semialdehyde dehydrogenase of Escherichia coli K-12 was located at min 34.1 on the genetic map.
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    Effects of pantolactone and butyrolaectone on the pleiotropic phenotypes of lon mutants and on thermal induction of the SOS phenomena in a tif mutant of Escherichia coli K12 (1982)
    Springer
    Archives of microbiology 132 (1982), S. 308-312 
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    ISSN: 1432-072X
    Keywords: Escherichia coli ; lon mutant ; tif mutant ; Pantolactone ; Butyrolactone ; SOS functions ; Filament formation ; Phage induction ; Lysogenization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pantolactone and butyrolactone, known to suppress cell filament formation in the lon mutant of Escherichia coli, were found also to be capable of partially correcting other anomalies of the mutant including impaired lysogenization with bacteriophages lambda and Pl and increased synthesis of colanic acid. In contrast to pantolactone, which inhibited thermal induction of cell filament formation and lambda prophage in the tif mutant as previously described, butyrolactone enhanced these phenomena. It was inferred that whereas these substances exert their effects through acting upon the tif-recA protein in the tif bacterium, there is a distinct target for their characteristic actions in the lon mutant.
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    How close to the theoretical diffusion limit do bacterial uptake systems function? (1982)
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    Archives of microbiology 131 (1982), S. 36-42 
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    ISSN: 1432-072X
    Keywords: Escherichia coli ; Growth rate ; Low nutrient concentration ; Precision measurement ; Diffusion-limited growth ; Theoretical maximum growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using a 10cm flow-through cuvette in a high precision spectrophotometer linked to a mini-computer, the growth rate dependence of Escherichia coli on glucose concentration has been studied. The specific growth rate vs bacterial mass of single cultures consuming small amounts of glucose was followed. The data were analyzed with the computer programs described previously. For neither batch nor chemostat-cultured organisms did growth follow the monod growth law. Rather, the growth rate vs residual glucose concentration has an almost abrupt change in slope, indicative of a passive diffusion barrier prior to an uptake system possessing hyperbolic dependency. Calculations showed that the diffusion through the outer membrane via the porin channels could quantitatively account for the deviations from hyperbolic dependency. Long term chemostat culture alters the bacteria so that the maximum specific growth rate is reduced, but the initial dependence on glucose concentration is increased approaching more closely the theoretical limit. Therefore there was both a change in the outer membrane channels and the uptake activity of the cytoplasmic membrane.
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    On the precision and accuracy achieved by Escherichia coli cells at fission about their middle (1982)
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    Archives of microbiology 131 (1982), S. 55-59 
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    ISSN: 1432-072X
    Keywords: Escherichia coli ; Cell division ; Bacterial morphology ; Symmetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Length and width of each of the prospective siblings of constricted Escherichia coli cells from different strains and culture conditions were measured from electron micrographs. The data were statistically analyzed to investigate how equally the length and volume of one cell was divided into two. The analysis showed that, for all cultures, bipartition is unbiased or very nearly so, i.e. sibling cells were on the average equally long and large. The precision of bipartition attained by the cells was usually high; it was related to the average cell shape (length/width): slender E. coli cells divided into two less precisely than squat cells. Absolute size, growth rate and strain specificity affected the precision of bipartition only indirectly, i.e. in as much as they influenced cell shape.
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    Lipoic acid content of Escherichia coli and other microorganisms (1975)
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    Archives of microbiology 106 (1975), S. 259-266 
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    ISSN: 1432-072X
    Keywords: Lipoic acid assay ; Escherichia coli ; Microbial lipoic acid content ; Pyruvate dehydrogenase complex ; α-Ketoglutarate dehydrogenase complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A mutant strain of Escherichia coli K12 requiring lipoic acid, W1485 lip 2 (ATCC 25645), was used to develop a turbidimetric assay for lipoic acid and a polarographic assay based on the oxidation of pyruvate by suspensions of lipoic acid-deficient organisms. The turbidimetric assay was more sensitive with a working range equivalent to 0.2–2.0 ng of dl-α-lipoic acid compared with 5–50 ng for the polarographic method. The mutant responded equally to racemic mixtures of α-lipoic acid, β-lipoic acid and dihydrolipoic acid but gave little response to lipoamide, and other derivatives without prior hydrolysis; 8-methyllipoic acid was a competitive inhibitor of the response to lipoic acid. A high specificity of the mutant for the natural stereoisomer was indicated by the fact that (+)-α-lipoic acid had twice the activity of the racemic mixture. Escherichia coli K12 contained less than 0.05 ng of free (+)-α-lipoic acid per mg dry weight but, depending on the growth substrate, the equivalent of between 13 and 47 ng of (+)-α-lipoic acid per mg dry weight after acid extraction. There was a strong correlation between the lipoic acid content and the sum of the specific activities for the pyruvate and α-ketoglutarate dehydrogenase complexes. Experiments with washed suspensions of Escherichia coli showed only small increases in lipoic acid content (18%) when incubated with pyruvate, cysteine and methionine. When supplied with exogenous lipoic acid the mutant, W1485 lip 2, accumulated very little more than was demanded by its metabolism. The lipoic acid contents of several organisms were measured and correlated with their metabolism.
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    ld-Carboxypeptidase activity in Escherichia coli (1986)
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    Archives of microbiology 144 (1986), S. 181-186 
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    ISSN: 1432-072X
    Keywords: Antibiotics ; d-Amino acids ; ld-Carboxypeptidase ; Escherichia coli ; Murein synthesis ; Nocardicin A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A ld-carboxypeptidase from Escherichia coli K 12 was isolated by Tris-EDTA treatment and purified to electrophoretic homogeneity by DEAE-cellulose chromatography. The enzyme has a molecular weight of approximately 12,000 as determined by sodium dodecyl sulfatepolyacrylamide electrophoresis and by Sephadex G-100 gel filtration. The studies of the substrate specificity of the enzyme revealed that UDP-MurNAc-tetrapeptide is a superior substrate, with a K m value of 1×10-4 mol/l. The activity of the ld-carboxypeptidase was inhibited by d-amino acids and the β-lactam antibiotic nocardicin A. K i values of 0.3 and 43 mmol/l were determined for nocardicin A and d-homoserine, respectively. The properties of the purified enzyme correspond to activity I in ether treated cells.
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    Betaine modulates intracellular thiol and potassium levels in Escherichia coli in medium with high osmolarity and alkaline pH (1995)
    Springer
    Archives of microbiology 163 (1995), S. 76-78 
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    ISSN: 1432-072X
    Keywords: Key words Betaine ; Thiols ; Potassium ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glycine betaine stimulates the growth rate of various bacteria in high osmolarity medium. In our studies, glycine betaine stimulated the growth rate of Escherichia coli K12 in minimal medium with normal osmolarity at alkaline pH (pH 8.2). Betaine also caused a reduction in the intracellular pools of K+ and low molecular weight thiols in E. coli growing both in medium with high osmolarity and at alkaline pH. These effects of betaine were absent at pH 7.0. In cells growing in high osmolarity medium, 10 mM sodium acetate or 10 μM N-ethylmaleimide reduced expression of the osmosensitive gene proU to the same extent as treatment with betaine; however, under these conditions, sodium acetate and N-ethylmaleimide did not stimulate the growth of E. coli. It is proposed that low molecular weight thiols and intracellular pH may participate in the response of E. coli to betaine.
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    Escherichia coli and other species of the Enterobacteriaceae encode a protein similar to the family of Mip-like FK506-binding proteins (1995)
    Springer
    Archives of microbiology 163 (1995), S. 357-365 
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    ISSN: 1432-072X
    Keywords: Key wordsmip Gene ; Mip protein ; FK506-binding proteins ; FKBP ; Legionella pneumophila ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A newly identified gene in Escherichia coli, fkpA, encodes a protein with extensive similarity to the macrophage infectivity potentiator (Mip) proteins of Legionella pneumophila and Chlamydia trachomatis. The FkpA protein may be a new member of the family of FK506-binding proteins (FKBPs) because its carboxyl domain includes a sequence that matches the consensus FK506-binding motif in 40 of 48 positions, including those amino acids at the active site that form hydrogen bonds with the drug FK506. The amino acid sequence of the 29 kDa FkpA protein is 30–35% identical to the Mip proteins of L. pneumophila, L. micdadei, and C. trachomatis. Of the 270 amino acids of FkpA, 113 (42%) are identical to the sequence of one or another of these Mip proteins. Overexpression of FkpA or deletion of fkpA from the E. coli chromosome had no detrimental effect on bacterial growth, indicating that fkpA is not an essential gene. Hybridization of fkpA-specific DNA probes to genomic blots revealed that similar genes exist in several representatives of the Enterobacteriaceae. Thus, mip-like genes are not found exclusively in bacteria having a predominately intracellular life style, but instead appear to be a new FKBP subfamily that is a common constituent of many bacteria.
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    Effects of iron-limitation ofEscherichia coli on growth, the respiratory chains and gallium uptake (1986)
    Springer
    Archives of microbiology 146 (1986), S. 80-86 
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    ISSN: 1432-072X
    Keywords: Iron-limitation ; Escherichia coli ; Respiratory chains ; Cytochromes ; Gallium ; Metal uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of iron limitation on growth, the composition and function of the respiratory chains, and gallium uptake inEscherichia coli have been studied. Decreasing the iron concentration in a defined medium using Chelex resin gave lower growth yields in both continuous culture and prolonged batch culture. In the former, ironlimited (entering [Fe]≤2.0 μM) cells exhibited diminished respiration rates, respiration-driven proton translocation quotients, and levels of non-haem iron and cytochromes. The cellular concentration of haemoproteinb-590 (a cytochromea 1-like hydroperoxidase) decreased 20-fold on iron limitation, whilst a CO-binding pigment with an absorption maximum in the dithionite-treated form near 500 nm appeared. Gallium(III) (9 μM) added to iron-limited, but not iron-sufficient, cultures diminished growth yields further; cells grown with low entering concentrations of iron took up less gallium than iron-sufficient cells. These results are attributed to the interference by gallium(III) with siderophore-mediated metal uptake. Gallium also stimulated iron uptake and was itself accumulated by iron-sufficient cells, suggesting that gallium(III) also affects the iron transport system(s) of low affinity.
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    Cytosine deaminase that hydrolyzes creatinine to N-methylhydantoin in various cytosine deaminase-forming microorganisms (1987)
    Springer
    Archives of microbiology 147 (1987), S. 58-63 
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    ISSN: 1432-072X
    Keywords: Creatinine deimination enzymes ; Creatinine deiminase ; Cytosine deaminase ; Creatinine degradation ; N-Methylhydantoin ; Creatinine ; Cytosine ; Pseudomonas putida 77 ; Cytosine deaminase induction ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Creatinine deimination has been newly detected in the following various cytosine deaminase-forming microorganisms: Escherichia coli, Proteus mirabilis, Pseudomonas aureofaciens, Pseudomonas chlororaphis and Pseudomonas cruciviae. All these microorganisms, except for E. coli, formed cytosine deaminase in a constitutive or repressive way. P. putida 77 and E. coli showed highly increased formation of creatinine deiminase in the presence of creatinine and cytosine. Throughout serial DEAE-Sephacel and Sephacryl S-300 column chromatographies, the cytosine deaminases of these microorganisms, except for that of P. ovalis, were found to hydrolyze both creatinine and cytosine at comparable rates. No concrete evidence was obtained for the presence of any other protein that hydrolyzed creatine and/or cytosine than the cytosine deaminases in the three test microorganisms randomly selected for investigation. Different from P. putida 77, none of the test microorganisms degraded N-methylhydantoin; neither N-methylhydantoin amidohydrolase nor N-carbamoylsarcosine amidohydrolase was formed in the presence of creatinine in these microorganisms. As a result, the wide occurrence of cytosine deaminases in microorganisms was found to be related to the wide distribution of those microorganisms which hydrolyze creatinine to N-methylhydantoin without further degradation.
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    The nucleotide sequence of the lipo-penicillinase gene of alkalophilic Bacillus sp. strain 170 (1989)
    Springer
    Archives of microbiology 151 (1989), S. 91-94 
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    ISSN: 1432-072X
    Keywords: Alkalophilic Bacillus ; Penicillinase ; β-Lactamase ; Class A enzyme ; Lipoprotein ; Amino acid homology ; Gene cloning ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The lipo-penicillinase (LIPEN) gene from an alkalophilic Bacillus sp. strain 170 was cloned in Escherichia coli using the vector pHSG399. A plasmid, pFAP121, was isolated from an ampicillin resistant transformant and the cloned LIPEN gene was found to be in a 2.2 kb DNA fragment. The nucleotide sequence of a 1.9 kb segment encoding the LIPEN was determined. This segment showed an open reading frame which would encode a polypeptide of 310 amino acids. The amino acid sequence of this LIPEN gene product has strong homology with those of the Bacillus cereus β-lactamase III and Bacillus licheniformis penicillinase.
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    Evolutionary relationship between Enterobacteriaceae: comparison of the ATP synthases (F1F0) of Escherichia coli and Klebsiella pneumoniae (1987)
    Springer
    Archives of microbiology 148 (1987), S. 187-192 
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    ISSN: 1432-072X
    Keywords: F1F0 ATP synthase ; Escherichia coli ; Klebsiella pneumoniae ; Phylogenetic relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ATP synthase complex of Klebsiella pneumoniae (KF1F0) has been purified and characterized. SDS-gel electrophoresis of the purified F1F0 complexes revealed an identical subunit pattern for E. coli (EF1F0) and K. pneumoniae. Antibodies raised against EF1 complex and purified EF0 subunits recognized the corresponding polypeptides of EF1F0 and KF1F0 in immunoblot analysis. Protease digestion of the individual subunits generated an identical cleavage pattern for subunits α, β, γ, ε, a, and c of both enzymes. Only for subunit δ different cleavage products were obtained. The isolated subunit c of both organisms showed only a slight deviation in the amino acid composition. These data suggest that extensive homologies exist in primary and secondary structure of both ATP synthase complexes reflecting a close phylogenetic relationship between the two enterobacteric tribes.
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    Carbonic anhydrase activity in acetate grown Methanosarcina barkeri (1989)
    Springer
    Archives of microbiology 151 (1989), S. 137-142 
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    ISSN: 1432-072X
    Keywords: Carbonic anhydrase ; Acetate metabolism ; Carbon monoxide dehydrogenase ; Methanosarcina barkeri ; Desulfobacter postgatei ; Desulfotomaculum acetoxidans ; Peptostreptococcus productus ; Methanococcus voltae ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell extracts (27000xg supernatant) of acetate grown Methanosarcina barkeri were found to have carbonic anhydrase activity (0.41 U/mg protein), which was lost upon heating or incubation with proteinase K. The activity was inhibited by Diamox (apparent K i=0.5 mM), by azide (apparent K i=1 mM), and by cyanide (apparent K i=0.02 mM). These and other properties indicate that the archaebacterium contains the enzyme carbonic anhydrase (EC 4.2.1.1). Evidence is presented that the protein is probably located in the cytoplasm. Methanol or H2/CO2 grown cells of M. barkeri showed no or only very little carbonic anhydrase activity. After transfer of these cells to acetate medium the activity was “induced” suggesting a function of this enzyme in acetate fermentation to CO2 and CH4. Interestingly, Desulfobacter postgatei and Desulfotomaculum acetoxidans, which oxidize acetate to 2 CO2 with sulfate as electron acceptor, were also found to exhibit carbonic anhydrase activity (0.2 U/mg protein).
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    Pyrimidine, purine and nitrogen control of cytosine deaminase synthesis in Escherichia coli K12. Involvement of the glnLG and purR genes in the regulation of codA expression (1989)
    Springer
    Archives of microbiology 152 (1989), S. 115-118 
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    ISSN: 1432-072X
    Keywords: Escherichia coli ; codA ; glnLG ; purR ; Gene regulation ; Cytosine deaminase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cytosine deaminase, encoded by the codA gene in Escherichia coli catalyzes the deamination of cytosine to uracil and ammonia. Regulation of codA expression was studied by determining the level of cytosine deaminase in E. coli K12 grown in various defined media. Addition of either pyrimidine or purine nucleobases to the growth medium caused repressed enzyme levels, whereas growth on a poor nitrogen source such as proline resulted in derepression of cytosine deaminase synthesis. Derepression of codA expression was induced by starvation for either uracil or cytosine nucleotides. Nitrogen control was found to be mediated by the glnLG gene products, and purine repression required a functional purR gene product. Studies with strains harbouring multiple mutations affecting both pyrimidine, purine and nitrogen control revealed that the overall regulation of cytosine deaminase synthesis by the different metabolites is cumulative.
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    Glycine betaine reverses the effects of osmotic stress on DNA replication and cellular division in Escherichia coli (1988)
    Springer
    Archives of microbiology 149 (1988), S. 232-239 
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    ISSN: 1432-072X
    Keywords: Turgor ; Glycine betaine ; K+ ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The accumulation of glycine betaine to a high internal concentration by Escherichia coli cells in high osmolarity medium restores, within 1 h, a subnormal growth rate. The experimental results support the view that cell adaptation to high osmolarity involves a decrease in the initiation frequency of DNA replication via a stringent response; in contrast, glycine betaine transport and accumulation could suppress the stringent response within 1–2 min and restore a higher initiation frequency. High osmolarity also triggers the cells to lengthen, perhaps via an inhibition of cellular division; glycine betaine also reverses this process. It is inferred that turgor could control DNA replication and cell division in two separate ways. Glycine betaine action is not mediated by K+ ions as the internal level of K+ ions is not modified significantly following glycine betaine accumulation.
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    Different physiological roles of two independent pathways for nitrite reduction to ammonia by enteric bacteria (1990)
    Springer
    Archives of microbiology 154 (1990), S. 349-354 
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    ISSN: 1432-072X
    Keywords: Nitrite reduction ; Anaerobic regulation ; NarL protein ; Two-component regulatory systems ; Anaerobic respiration ; Nitrite detoxification ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Operon fusion strains and mutants of Escherichia coli K-12 lacking the NADH-dependent nitrite reductase have been used to determine the regulation and physiological roles of two independent pathways for nitrite reduction to ammonia. Both the formate-and NADH-dependent pathways (Nrf and Nir, respectively) were totally repressed during aerobic growth, partially active during anaerobic growth in the absence of nitrite and further induced anaerobically by nitrite. Both were dependent upon a functional Fnr protein (a transcription activator of genes for anaerobic respiration). During anaerobic growth in the presence of nitrate, the Nir pathway was fully induced but Nrf was strongly repressed. Mutants defective in the NarL protein, which induces transcription of nitrate reductase genes but represses fumarate reductase genes in the presence of nitrate, were derepressed for Nrf activity during growth with nitrate, but the Nir enzyme was less active. The synthesis of Nrf components was also sensitive to glucose repression and weak activation by NarL during growth in the absence of nitrate. These data indicate that the Nir pathway provides a mechanism for detoxifying nitrite formed in the cytoplasm as a product of nitrate reduction. In contrast, the electrogenic reduction of nitrite by the Nrf pathway provides a secondary source of energy during anaerobic growth and is consequently repressed by the NarL protein when the thermodynamically more favourable electron acceptor, nitrate, is available. Two short DNA sequences, 5′-TACCAT-3′ and 5′-CTCCTT-3′, were found in the promoters of operons known to be activated or repressed by the NarL protein. It is proposed that NarL activates nir B transcription by binding to one or both of these sequences located 5′ to the RNA polymerase binding site, but represses other operons, including nrf, by binding close to the transcription start.
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    Construction of stable, single-copy luciferase gene fusions in Escherichia coli (1991)
    Springer
    Archives of microbiology 156 (1991), S. 444-448 
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    ISSN: 1432-072X
    Keywords: Transposon5 ; Xylose operon ; Transcriptional fusions ; ColE1 replication ; luxAB genes ; Escherichia coli ; Vibrio harveyi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A ColE1-based plasmid for transcriptional gene fusions was constructed that contains both the promoterless luxAB genes of Vibrio harveyi and a tet marker within the inverted repeats of a left end-truncated Tn5 element. Introduction of this plasmid into an Escherichia coli strain containing a plasmid (pTF421) that overproduces ColE1 RNA1 (and thus inhibits replication of the ColE1 plasmid) allowed selection for cells that had a single copy of the luxAB operon transposed into the chromosome beginning 5 days post-transformation. The long latent period necessary for Tn5 transposition is analogous to that found in other systems, where transposition frequencies and mutation rates increase in a time-dependent manner when selected for upon prolonged incubation on Petri dishes under bacteriostatic conditions.
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    Aluminium toxicity and binding to Escherichia coli (1991)
    Springer
    Archives of microbiology 156 (1991), S. 507-512 
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    ISSN: 1432-072X
    Keywords: Aluminium and bacteria ; Metal speciation ; Iron transport ; Biosorption of metals ; Metal-microbe interactions ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The toxicity and binding of aluminium to Escherichia coli has been studied. Inhibition of growth by aluminium nitrate was markedly dependent on pH; growth in medium buffered to pH 5.4 was more sensitive to 0.9 mM or 2.25 mM aluminium than was growth at pH 6.6–6.8. In medium buffered with 2-(N-morpholino)ethanesulphonic acid (MES), aluminium toxicity was enhanced by omission of iron from the medium or by use of exponential phase starter cultures. Analysis of bound aluminium by atomic absorption spectroscopy showed that aluminium was bound intracellularly at one type of site with a K m of 0.4 mM and a capacity of 0.13 mol (g dry wt)-1. In contrast, binding of aluminium at the cell surface occurred at two or more sites with evidence of cooperativity. Addition of aluminium nitrate to a weakly buffered cell suspension caused acidification of the medium attributable to displacement of protons from cell surfaces by metal cations. It is concluded that aluminium toxicity is related to pH-dependent speciation [with Al(H2O) 6 3+ probably being the active species] and chelation of aluminium in the medium. Aluminium transport to intracellular binding sites may involve Fe(III) transport pathways.
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    Molecular organization of the Escherichia coli gab cluster: nucleotide sequence of the structural genes gabD and gabP and expression of the GABA permease gene (1993)
    Springer
    Archives of microbiology 160 (1993), S. 454-460 
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    ISSN: 1432-072X
    Keywords: Succinic semialdehyde dehydrogenase ; GABA permease ; Gab cluster ; REP elements ; GABA transport ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have determined the nucleotide sequences of two structural genes of the Escherichia coli gab cluster, which encodes the enzymes of the 4-aminobutyrate degradation pathway: gabD, coding for succinic semialdehyde dehydrogenase (SSDH, EC 1.2.1.16) and gabP, coding for the 4-aminobutyrate (GABA) transport carrier (GABA permease). We have previously reported the nucleotide sequence of the third structural gene of the cluster, gabT, coding for glutamate: succinic semialdehyde transaminase (EC 2.6.1.19). All three gab genes are transribed unidirectionally and their orientation within the cluster is 5′-gabD-gabT-gabP-3′. gabT and gabP are separated by an intergenic region of 234-bp, which contains three repetetive extragenic palindromic (REP) sequences. The gabD gene consists of 1,449 nucleotides specifying a protein of 482 amino acids with a molecular mass of 51.7 kDa. The protein shows significant homologies to the NAD+-dependent aldehyde dehydrogenase (EC 1.2.1.3) from Aspergillus nidulans and several mammals, and to the tumor associated NADP+-dependent aldehyde dehydrogenase (EC 1.2.1.4) from rat. The permease gene gabP comprises 1,401 nucleotides coding a highly hydrophobic protein of 466 amino acids with a molecular mass of 51.1 kDa. The GABA permease shows features typical for an integral membrane protein and is highly homologous to the aromatic acid carrier from E. coli, the proline, arginine and histidine permeases from Saccharomyces cerevisiae and the proline transport protein from A. nidulans. Uptake of GABA was increased ca. 5-fold in transformants of E. coli containing gabP plasmids. Strong overexpression of the gabP gene under control of the isopropyl-2-d-thiogalactoside (IPTG) inducible tac promoter, however, resulted in a severe growth inhibition of the transformed strains. The GABA carrier was characterized using moderately overexpressing transformants. The K m of GABA uptake was found to be 11.8 μM and the Vmax 0.33 nmol/min · mg cells. Uptake of GABA was stimulated by ammonium sulfate and abolished by 2,4-dinitrophenol. Aspartate competed with GABA for uptake.
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    Sequence divergence of the murB and rrfB genes from Escherichia coli and Salmonella typhimurium (1994)
    Springer
    Archives of microbiology 161 (1994), S. 501-507 
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    ISSN: 1432-072X
    Keywords: Escherichia coli ; Salmonella typhimurium ; murB ; rrfB ; Repetitive extragenic palindrome ; Evolution ; Mutation rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The murB gene of Salmonella typhimurium was cloned and found to be 75% and 82% identical to the DNA and protein sequences, respectively, of the same gene in Escherichia coli. These identities are among the lowest recorded between the two bacteria. Nevertheless, wild-type S. typhimurium murB complemented the known temperature-sensitive E. coli mutant, and wild-type E. coli murB complemented three temperature-sensitive mutants of S. typhimurium. The 5S rRNA gene, rrfB, and the region between murB and rrfB were also cloned and sequenced. The rrfB gene of S. typhimurium differs from rrfB of E. coli in only 2 of 120 nt, but the region between murB and rrfB has diverged greatly and includes a sequence that elosely resembles a repetitive extragenic palindrome of the type normally associated with E. coli. Previous comparisons of gene divergence have suggested that the chromosomal mutation rate is lower in the vicinity of the origin of replication. However, the S. typhimurium murB gene, located 6 map minutes from the origin of replication, is highly substituted at synonymous sites and the sequence between murB and rrfB is significantly modified as well. Thus, murB is an exception to the general observation that genes near the origin of replication show less divergence than do genes elsewhere in the bacterial chromosome.
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    Cell elongation and septation are two mutually exclusive processes in Escherichia coli (1997)
    Springer
    Archives of microbiology 168 (1997), S. 152-159 
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    ISSN: 1432-072X
    Keywords: Key words Bacterial shape ; Peptidoglycan ; β-Lactam ; antibiotics ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bacterial rod morphogenesis was studied in synchronously growing cells of Escherichia coli C600 during the reshaping process that follows the removal of mecillinam, a β-lactam antibiotic that specifically inhibits lateral wall formation of gram-negative rods and causes transition to coccal shape. Removal of mecillinam after 30 min of action did not affect the timing of subsequent cell division, but removal after 50 min delayed resumption of cell division for approximately one generation time. In order to study the interplay between lateral wall elongation and septum formation in determining and maintaining the bacterial rod shape, we evaluated the effect of re-adding mecillinam or of adding aztreonam (a specific inhibitor of septum formation) at various stages of the reshaping process. We conclude that mecillinam was active only during the reshaping process, while aztreonam was active only later when the cells were close to dividing again. These results provide further evidence for our previous proposal according to which elongation and septation are two alternating and competing events of the cell cycle and are linked to each other to force bacterial rods to grow to a given length.
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    Uptake and synthesis of compatible solutes as microbial stress responses to high-osmolality environments (1998)
    Springer
    Archives of microbiology 170 (1998), S. 319-330 
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    ISSN: 1432-072X
    Keywords: Key words Osmoregulation ; Stress protectants ; Trehalose ; Glycine betaine ; K+ uptake ; ABC ; transporters ; Efflux ; Gene regulation ; Escherichia coli ; Bacillus subtilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract All microorganisms possess a positive turgor, and maintenance of this outward-directed pressure is essential since it is generally considered as the driving force for cell expansion. Exposure of microorganisms to high-osmolality environments triggers rapid fluxes of cell water along the osmotic gradient out of the cell, thus causing a reduction in turgor and dehydration of the cytoplasm. To counteract the outflow of water, microorganisms increase their intracellular solute pool by amassing large amounts of organic osmolytes, the so-called compatible solutes. These osmoprotectants are highly congruous with the physiology of the cell and comprise a limited number of substances including the disaccharide trehalose, the amino acid proline, and the trimethylammonium compound glycine betaine. The intracellular amassing of compatible solutes as an adaptive strategy to high-osmolality environments is evolutionarily well-conserved in Bacteria, Archaea, and Eukarya. Furthermore, the nature of the osmolytes that are accumulated during water stress is maintained across the kingdoms, reflecting fundamental constraints on the kind of solutes that are compatible with macromolecular and cellular functions. Generally, compatible solutes can be amassed by microorganisms through uptake and synthesis. Here we summarise the molecular mechanisms of compatible solute accumulation in Escherichia coli and Bacillus subtilis, model organisms for the gram-negative and gram-positive branches of bacteria.
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    Toxicity and accumulation of thallium in bacteria and yeast (1976)
    Springer
    Archives of microbiology 110 (1976), S. 279-286 
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    ISSN: 1432-072X
    Keywords: Thallium accumulation ; Saccharomyces cerevisiae ; Escherichia coli ; Bacillus megaterium KM ; Thallium toxicity ; Potassium ; Microbial growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thallium sulphate inhibited microbial growth, withBacillus megaterium KM, more sensitive to the metal thanSaccharomyces cerevisiae andEscherichia coli. Inhibition ofB. megaterium KM andS. cerevisiae, but not ofE. coli, was alleviated by increasing the potassium concentration of the medium; inhibition of respiration ofS. cerevisiae, but not ofE. coli, was similarly alleviated. Thallium was rapidly bound, presumably to cell surfaces, byS. cerevisiae andE. coli, and was progressively accumulated by energy-dependent transport systems (probably concerned primarily with potassium uptake) with both organisms. Thallium uptake kinetics suggested more than one transport system operated in yeast, possibly reflecting a multiplicity of potassium transport systems. ApparentK m andK i values for competitive inhibition of thallium uptake by potassium indicatedS. cerevisiae to have a higher affinity for thallium uptake than for potassium, whileE. coli had a transport system with a higher affinity for potassium than for thallium. The likely systems for thallium transport are discussed. A mutant ofE. coli with tenfold decreased sensitivity to thallium was isolated and apparently effected surface binding of thallium in amounts equivalent to the wild type organism, but showed no subsequent uptake and accumulation of the metal from buffer, even though it was able to accumulate potassium to normal intracellular concentrations during growth.
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    Behaviour of dictyostelium discoideum amoebae and Escherichia coli grown together in chemostat culture (1976)
    Springer
    Archives of microbiology 109 (1976), S. 187-194 
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    ISSN: 1432-072X
    Keywords: Predator-prey ; Slime moulds ; Ecological enrichment ; Stability ; Dictyostelium discoideum ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When Dictyostelium discoideum amoebae and Escherichia coli were grown together in chemostat culture damped oscillations in the popullation densities of the organisms occurred followed by a sudden increase in bacterial numbers and a concommitant decrease in the number of amoebae. After the system had come to equilibrium altering the dilution rate resulted in a monotonic change in the experimental variables to new steady state levels. A square wave increase in the concentration of limiting nutrient in the feed medium during the oscillatory phase of culture produced a sinusoidal response indistinguishable from that prior to the perturbation. The results are more complicated than those predicted by simple models of microbial predator-prey dynamics although they correspond most nearly to models which incorporate saturation kinetics.
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    Protoplast-like structures formation from two species of enterobacteriaceae by fosfomycin treatment (1978)
    Springer
    Archives of microbiology 118 (1978), S. 219-221 
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    ISSN: 1432-072X
    Keywords: Protoplasts ; Fosfomycin ; Escherichia coli ; Serratia marcescens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A procedure for protoplasts formation from Escherichia coli and Serratia marcescens by treatment with fosfomycin alone is described. This method gives high and low yields of stable protoplasts from E. coli and S. marcescens respectively. In the last case numerous spheroplasts were obtained. Electron micrographs of intact cells, protoplasts and spheroplasts are shown.
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    Accumulation of pyrophosphate in Escherichia coli. Relationship to growth and nucleotide synthesis (1983)
    Springer
    Archives of microbiology 136 (1983), S. 209-211 
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    ISSN: 1432-072X
    Keywords: Escherichia coli ; pyrophosphate ; nucleotide synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pyrophosphate (PPi) content of Escherichia coli is increased manyfold when the growth of the cells is limited by inhibition of the synthesis of nucleotides. The accumulated PPi is immediately degraded when inhibition is released and growth allowed to resume. Other tested nutritional deficiences (starvation of carbon source, sulfate or an amino acid) fail to induce PPi accumulation.
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    Transport and metabolism of trehalose in Escherichia coli and Salmonella typhimurium (1984)
    Springer
    Archives of microbiology 137 (1984), S. 70-73 
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    ISSN: 1432-072X
    Keywords: Transport ; Trehalose ; Escherichia coli ; Salmonella typhimurium ; Trehalase ; Trehalose 6-phosphate hydrolase ; Phosphoenolpyruvate:trehalose phosphotransferase system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The metabolism of trehalose in wild type cells of Escherichia coli and Salmonella typhimurium has been investigated. Intact cells of Escherichia coli (grown on trehalose) accumulated [14C]-trehalose as [14C]-trehalose 6-phosphate. Toluene-treated cells catalyzed the synthesis of the [14C]-sugar phosphate from [14C]-trehalose and phosphoenolpyruvate; ATP did not serve as phosphoryl donor. Trehalose 6-phosphate could subsequently be hydrolyzed by trehalose 6-phosphate hydrolase, an enzyme which catalyzes the hydrolysis of the disaccharide phosphate into glucose and glucose 6-phosphate. Both Escherichia coli and Salmonella typhimurium induced this enzyme when they grew on trehalose. These findings suggest that trehalose is transported in these bacteria by an inducible phosphoenolpyruvate:trehalose phosphotransferase system. The presence of a constitutive trehalase was also detected.
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    Eubacteria have 3 growth modes keyed to nutrient flow (1984)
    Springer
    Archives of microbiology 137 (1984), S. 176-184 
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    ISSN: 1432-072X
    Keywords: Escherichia coli ; Paracoccus denitrificans ; Chemostat ; Recycling fermentor ; Growth yield ; Maintenance ; Nucleotide polyphosphates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aerobic growth of Escherichia coli and Paracoccus denitrificans has been studied in chemostat, fed batch, and recycling fermentor modes under carbon and energy limitation. Two abrupt drops or discontinuities in molar growth yield, Y, have been found that occur over relatively short ranges in the value of specific growth rate. Before the first discontinuity, Y is constant and maximal. After the first discontinuity, at a doubling time of 33 h, Y becomes constant again and independent of μ until the second discontinuity appears at a doubling time of about 50 h, corresponding to a μ of about 0.014. At this point, Y drops to a lower value that is constant at doubling times longer than 100 h, corresponding to a μ of about 0.007. The second discontinuity is associated in Paracoccus with elevated levels of guanosine tetraphosphate (ppGpp) that impose stringent regulation as has been found previously with Bacillus and Escherichia species. It is thus likely that the stringent response generally occurs in bacteria in vivo at a doubling time of about 50 h. The cause of the first discontinuity is unknown. All experiments indicate that Pirt-type calculations relating μ, Y, and maintenance energy demand are no longer valid. In chemostat experiments, the intercept of the relationship between specific substrate utilization and specific growth rate is defined as maintenance. However, this intercept most probably is caused by stringent regulation at low dilution rates. Three regions of bacterial growth rates are defined by this study, corresponding to doubling times of 0.5 to 15 h, 33 to 50 h, and 〉100 h. Some growth behavior in each region is unique to that region.
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    Expression of surface hydrophobicity encoded by R-plasmids in Escherichia coli laboratory strains (1984)
    Springer
    Archives of microbiology 138 (1984), S. 191-194 
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    ISSN: 1432-072X
    Keywords: R-plasmids ; Escherichia coli ; Surface hydrophobicity ; “Salting-out” ; Adherence to hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The inclusion of drug-resistance plasmids (R-plasmids) in Escherichia coli strains has been shown to determine the formation of specific surface structures which could modify bacterial surface characteristics relevant for pathogenic processes. Thirtyone R-plasmids (from different incompatibility groups) have been transferred to three E. coli laboratory strains, and surface hydrophobicity modifications have been measured by three methods: “salting-out”, adsorption to hexadecane and adsorption to xylene. The results obtained show that the presence of R-plasmids produced variations which are dependent on the receptor strains and measuring method employed. Also, it has been found that the plasmids behave differently depending on the strain in which they are included. The results obtained by the “salting-out” method are not correlative with those obtained by adsorption to hydrocarbons, probably due to the implication of different hydrophobic molecules in the interaction with salt or hydrocarbons. Concluding, the choice of receptor strain and measuring method are of great importance for the investigation of surface hydrophobicity (and probably other characteristics) encoded by R-plasmids.
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    Murein biosynthesis in ether permeabilized Escherichia coli starting from early peptidoglycan precursors (1981)
    Springer
    Archives of microbiology 130 (1981), S. 301-306 
    Details
    ISSN: 1432-072X
    Keywords: Escherichia coli ; Ether permeabilized cells ; Murein biosynthesis ; Inhibition ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract ETB, ether treated bacteria, from E. coli and other Gram-negative strains, contain in a cell-free system all enzymes necessary for murein biosynthesis. Starting with a variety of combinations of peptidoglycan precursors, high yields of sodium dodecylsulfate (SDS, 4%) insoluble murein or murein like material were synthesized. The amount of newly synthesized SDS insoluble material (NSM) was dependent upon the growing phase at which cells had been harvested for preparation of ETB. This data may provide some insight into the regulation of peptidoglycan biosynthesis. Starting from early peptidoglycan precursors, the cell-free synthesis of NSM was inhibited by specific inhibitors of murein synthesis, such as D-cycloserine, D-fluoroalanine, 2-amino-ethylphosphonate, analogues of D-alanyl-D-alanine and β-lactam antibiotics at appropriate concentrations. Some D-alanyl-D-alanine analogues and 4-chlorodiaminopimelic acid were incorporated into NSM in place of their corresponding natural substrates.
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    Nif plasmid from Lignobacter (1981)
    Springer
    Archives of microbiology 130 (1981), S. 322-324 
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    ISSN: 1432-072X
    Keywords: Lignobacter ; Salmonella typhimurium ; Escherichia coli ; Nif plasmid ; Tn9 ; Transduction ; Transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lignobacter strain K17 is able to degrade aromatic compounds and to fix atmospheric nitrogen. It was proved that capacity for nitrogen fixation by Lignobacter was plasmid mediated. Plasmid pUCS100 (17.5 Mdal) carrying nif genes was transferred from Lignobacter to Escherichia coli SK1592 and Salmonella typhimurium. The transposon Tn9 was translocated to pUCS100 to facilitate selection of Nif+ bacteria. E. coli SK1592 harboring the new plasmid (pUCS101) reduced acetylene under anaerobic conditions. Plasmids pUCS100 and pUCS101 were not stably maintained in E. coli and S. typhimurium.
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    Ethylene formation by cultures of Escherichia coli (1985)
    Springer
    Archives of microbiology 141 (1985), S. 209-213 
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    ISSN: 1432-072X
    Keywords: Escherichia coli ; Ethylene formation ; Methionine ; Secondary metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth of Escherichia coli strain B SPAO on a medium containing glucose, NH4Cl and methionine resulted in production of ethylene into the culture headspace. When methionine was excluded from the medium there was little formation of ethylene. Ethylene formation in methionine-containing medium occurred for a brief period at the end of exponential growth. Ethylene formation was stimulated by increasing the medium concentration of Fe3+ when it was chelated to EDTA. Lowering the medium phosphate concentration also appeared to stimulate ethylene formation. Ethylene formation was inhibited in cultures where NH4Cl remained in the stationary phase. Synthesis of the ethylene-forming enzyme system was determined by harvesting bacteria at various stages of growth and assaying the capacity of the bacteria to form ethylene from methionine. Ethylene forming capacity was greatest in cultures harvested immediately before and during the period of optimal ethylene formation. It is concluded that ethylene production by E. coli exhibits the typical properties of secondary metabolism.
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    In situ behaviour of D(-)-lactate dehydrogenase from Escherichia coli (1984)
    Springer
    Archives of microbiology 139 (1984), S. 255-259 
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    ISSN: 1432-072X
    Keywords: Lactate dehydrogenase ; Escherichia coli ; In situ ; In vitro ; Kinetic properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Some kinetic properties of the D(-)-lactate dehydrogenase (EC 1.1.1.28) of Escherichia coli have been investigated. There were marked differences between the kinetic properties of the enzyme studied in situ compared with the in vitro D(-)-lactate dehydrogenase. D(-)-Lactate dehydrogenase in situ showed high substrate inhibition with pyruvate over the pH range 6.0–7.0, whereas the enzyme in vitro did not. The pH optimum for pyruvate reduction by the in situ D(-)-lactate dehydrogenase ranged between pH 7.5 and 7.8, whereas the in vitro enzyme showed its pH optimum between pH 6.8 and 7.0. The pK values of the prototropic groups that controlled the enzymatic activity shift to the acidic region for the in vitro enzyme with respect to the in situ enzyme. In vitro D(-)-lactate dehydrogenase exhibits homotropic interactions with its substrate, pyruvate and its coenzyme, NADH, at pH values ranging between pH 6.0 and 8.5, but the in situ enzyme showed homotropic interactions neither with pyruvate nor with NADH at all pH values studied.
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    Genetic manipulation of the restricted facultative methylotroph Hyphomicrobium X by the R-plasmid-mediated introduction of the Escherichia coli pdh genes (1984)
    Springer
    Archives of microbiology 139 (1984), S. 311-318 
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    ISSN: 1432-072X
    Keywords: Hyphomicrobium X ; Methylotrophy ; Escherichia coli ; Pyruvate dehydrogenase ; Genetic manipulation ; Phage Mu ; R-Plasmids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The inability of Hyphomicrobium X to grow on compounds such as pyruvate and succinate is most likely due to the absence of a functional pyruvate dehydrogenase (PDH) complex. Further support for this was sought by studying the effect of the introduction of the Escherichia coli pdh genes in Hyphomicrobium X on the pattern of substrate utilization by the latter organism. These genes were cloned by in vivo techniques using the broad-host range conjugative plasmid RP4: :Mucts. Plasmid RP4 derivatives containing pdh genes were selected by their ability to complement a pyruvate dehydrogenase deletion mutant of E. coli, strain JRG746 recA (ace-1pd) Δ18. The plasmids thus obtained could be transferred through an intermediary host (C600 recA), selecting only for an antibiotic resistance coded for by RP4 and back into JRG746 or other E. coli pdh mutants, upon which they still conferred the wild type phenotype. Enzyme assays showed that the latter strains, when carrying plasmid RP4′ pdh1 also possessed PDH complex activity. Conjugation between the auxotrophic E. coli JRG746 (RP4′ pdh1) strain and Hyphomicrobium X on pyruvate minimal agar gave rise to progeny which, on the basis of its morphology (stalked bacteria), their ability to grow on C1-compounds and to denitrify (now also with pyruvate) were identified as hyphomicrobia. This Hyphomicrobium X transconjugant was also able to grow in minimal medium with succinate, but no other novel growth substrates have been identified so far. An analysis of protein extracts with 2-dimensional gel electrophoresis indicated that Hyphomicrobium X and JRG746 only synthesized all three components of the PDH complex when carrying plasmid RP4′ pdh1. These results are compatible with the suggested significance of the lack of a functional PDH complex in wild type Hyphomicrobium X.
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    Exchange of colicin receptor capacity between strains of Escherichia coli sensitive or resistant to colicin K-K235 (1982)
    Springer
    Archives of microbiology 131 (1982), S. 229-234 
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    ISSN: 1432-072X
    Keywords: Colicin K ; Phage T6 ; tsx mutants ; Outer membrane ; Reconstitution ; EDTA treatment ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phage and colicin-resistant mutants were derived from Escherichia coli K-12P678. Two classes of phage T6 and colicin K-resistant mutants (genotype tsx) were isolated. Tsx-2 mutants, which demonstrated mucoid growth and increased sensitivities to many antibiotics, became sensitive to colicin K when pretreated with ethylenediaminetetraacetate (EDTA), whereas Tsx-1 mutants did not. Reassociation of EDTA-released material partially restored resistance to colicin K for Tsx-2 mutants. When EDTA-released material from strain P678 was associated with either class of K-resistant mutant, an increase in colicin K sensitivity resulted. Observations suggest that colicin K can act on its target site once it penetrates the cell surface. In addition, results suggest that functional colicin K receptors can be transferred from sensitive to resistant strains, thus conferring colicin sensitivity.
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    Effects of temperature on the size and shape of Escherichia coli cells (1982)
    Springer
    Archives of microbiology 131 (1982), S. 235-240 
    Details
    ISSN: 1432-072X
    Keywords: Escherichia coli ; Temperature ; Morphology ; Cell shape ; Cell size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two substrains of Escherichia coli B/r were grown to steady-state in batch cultures at temperatures between 22 and 42° C in different growth media. The size and shape of the cells were measured from light and electron micrographs and with the Coulter channelizer. The results indicate that cells are shorter and somewhat thicker at the lower temperatures, especially in rich growth media; cell volume is then slightly smaller. A lower temperature was further found to increase the relative duration of the constriction period. The shapes of the cell size distributions are indistinguishable, indicating that the pattern of growth of the cells is the same at all temperatures. The adaptation of the cells to a temperature shift lasted several generations, indicating that the morphological effects of temperature are mediated by the cell's physiology.
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    Filamentous growth of Escherichia coli K12 elicited by dimeric, mixed-valence complexes of ruthenium (1984)
    Springer
    Archives of microbiology 139 (1984), S. 265-271 
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    ISSN: 1432-072X
    Keywords: Cell division ; Escherichia coli ; Ruthenium compounds ; Filament formation ; Mutagenesis ; Cell cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dimeric, mixed-valence [(Ru(II), Ru(III)] compounds of ruthenium caused filament formation in growing cultures of Escherichia coli K12. Three compounds with the general formula Ru2(NH3)6X5 · H2O (where X is a halide) were tested; in order of decreasing effectiveness (and with the concentration giving maximum effect), these were the bromo (10-5 M), chloro (10-4 to 10-5 M), and iodo (10-3 to 10-4 M) analogues. Filamentation elicited by the bromo and chloro compounds was spontaneously reversible after 3–4 h, and tentatively attributed to oxidation of the active mixed-valence form to inactive Ru(III) complexes. Several compounds known to accelerate division of filaments formed under other conditions were ineffective in reversing the filamentation, but the presence of 0,43 M-dimethylsulphoxide totally inhibited filamentation caused by the bromo or chloro compounds and by cis-Pt(NH3)2Cl2 (cisplatin), an established filamenting and antitumour agent. The ruthenium complexes bound to mammalian DNA, but were without effect on the UV spectrum or cellular content of DNA in E. coli, despite showing marked mutagenic activity in reverse mutation tests with Salmonella typhimurium. Cells remained sensitive to inhibition of division by the ruthenium complexes until immediately prior to the division event. Possibilities for the (probably complex) mode of action and the potential of related compounds for therapeutic use are discussed.
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    Regulation of the synthesis of hydrogenase (formate hydrogen-lyase linked) of E. coli (1984)
    Springer
    Archives of microbiology 139 (1984), S. 299-304 
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    ISSN: 1432-072X
    Keywords: Hydrogenase ; Regulatory mutants ; Formate hydrogen-lyase ; Escherichia coli ; hyd::lac fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The regulation of synthesis of the hydrogenase which is a component of the formate hydrogen-lyase complex was studied by means of a strain of Escherichia coli possessing a transcriptional fusion of the hydrogenase gene (hyd) with the lacZ gene (hyd::lac fusion). Formation of active hydrogenase in the wild strain requires the presence of nickel in the medium; transcription of the hyd gene, however, is independent from the prescence of Ni2+. Ni2+ addition to Ni2+-prestarved cells did not lead to any activation of presumptive hydrogenase apoprotein. Regulatory mutants were isolated in which nitrate repression of hyd::lac expression was relieved. Two main classes of regulatory mutants were identified: (i) Mutants with a defect in nitrate reductase; (ii) mutants with a cis-dominant regulatory mutation closely linked to the hyd::lac fusion. In the presence of formate which acts as an inducer, the hyd::lac fusion was also expressed under aerobic conditions. The results infer that nitrate repression of transcription of the hydrogenase structural gene is not effected by nitrate itself but requires the function of the electron transport chain leading to nitrate and that mutations in the promoter/operator region of the hyd cistron may confer insensitivity to redox control both by oxygen and nitrate.
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    Expression of genes from the marine bacteriumAlteromonas haloplanktis 214 inEscherichia coli K-12 (1985)
    Springer
    Archives of microbiology 142 (1985), S. 248-252 
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    ISSN: 1432-072X
    Keywords: Alteromonas haloplanktis ; Marine bacteria ; Escherichia coli ; Gene bank ; Gene expression ; Plasmids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA from the marine bacteriumAlteromonas haloplanktis 214 was partially digested withSau 3A and inserted into theBam HI site of the cloning vector pBR322. The ligation mixture was used to transformEscherichia coli HB101. The gene bank plasmid preparation obtained was used to transformEscherichia coli K-12 strain EO2717, an organism auxotrophic for histidine, arginine, adenine, uracil and thiamin. Prototrophic transformants for each of the five metabolites were isolated using appropriate minimal media for selection. Plasmids isolated from each of the transformants were shown by hybridization to containA. haloplanktis DNA and to be capable of complementing the appropriate mutation inE. coli EO2717. Restriction maps showed that each of the plasmids was different.
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    Influence of growth environment on the phosphoenolpyruvate: Glucose phosphotransferase activities of Escherichia coli and Klebsiella aerogenes: A comparative study (1980)
    Springer
    Archives of microbiology 125 (1980), S. 175-179 
    Details
    ISSN: 1432-072X
    Keywords: Escherichia coli ; Klebsiella aerogenes ; Glucose uptake ; Glucose: Phosphoenolpyruvate phosphotransferase activities ; Chemostat culture ; Glucose-limitation ; Potassium-limitation ; Ammonia-limitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A consistent difference was found between glucose-limited cultures of Escherichia coli and Klebsiella aerogenes strains in the manner which their apparent cellular content of glucose: phosphoenolpyruvate phosphotransferase (glucose-PTS) varied with growth rate. With the former strains, activity increased as a function of growth rate; in the latter it decreased. However, under glucose-sufficient conditions (potassium-or ammonia-limitation) both species behaved similarly; the glucose-PTS activity was lower and bore no obvious relationship to the rate of glucose consumption expressed by the growing culture. These results are discussed in relation to the role of glucose as a regulator of glucose-PTS synthesis, and to the likely contribution which the glucose-PTS makes to the overall rate of glucose uptake, particularly by cells growing in glucose-sufficient environments.
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    ld-Carboxypeptidase activity in Escherichia coli (1986)
    Springer
    Archives of microbiology 144 (1986), S. 175-180 
    Details
    ISSN: 1432-072X
    Keywords: d-Amino acids ; ld-carboxypeptidase ; Escherichia coli ; Ether treated cells ; Thienamycin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The activities of the ld-carboxypeptidases of Escherichia coli K12 and of a mutant strain 155 with reduced activities were studied with the aid of ether treated cells. Evidence was obtained that was consistent with the suggestion that in both strains two ld-carboxypeptidase activities are present. Activity I degrades the nucleotide activated precursor UDP-MurNAc-tetrapeptide and activity II splits off d-alanine residues from position 4 of the peptide subunits in the nascent murein. In the mutant strain activity I is reduced 10fold compared with strain K 12, whereas activity II is not affected. The two activities could be distinguished with regard to their sensitivity to d-amino acids and the β-lactam antibiotic thienamycin.
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    betaine modulates intracellular thiol and potassium levels in Escherichia coli in medium with high osmolarity and alkaline pH (1995)
    Springer
    Archives of microbiology 163 (1995), S. 76-78 
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    ISSN: 1432-072X
    Keywords: Betaine ; Thiols ; Potassium ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glycine betaine stimulates the growth rate of various bacteria in high osmolarity medium. In our studies, glycine betaine stimulated the growth rate of Escherichia coli K 12 in minimal medium with normal osmolarity at alkaline pH (pH 8.2). Betaine also caused a reduction in the intracellular pools of K+ and low molecular weight thiols in E. coli growing both in medium with high osmolarity and at alkaline pH. These effects of betaine were absent at pH 7.0. In cells growing in high osmolarity medium, 10 mM sodium acetate or 10 μM N-ethylmaleimide reduced expression of the osmosensitive gene proU to the same extent as treatment with betaine; however, under these conditions, sodium acetate and N-ethylmaleimide did not stimulate the growth of E. coli. It is proposed that low molecular weight thiols and intracellular pH may participate in the response of E. coli to betaine.
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    Properties of the purified APS-kinase from Escherichia coli and Saccharomyces cerevisiae (1986)
    Springer
    Archives of microbiology 145 (1986), S. 32-38 
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    ISSN: 1432-072X
    Keywords: Sulphate assimilation ; Adenylylsulphate 3′-phosphotransferase EC 2.7.1.25 ; Escherichia coli ; Saccharomyces cerevisiae ; Enzyme purification ; Enzyme regulation ; Thiredoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Adenylylsulphate kinase (EC 2.7.1.25, ATP:adenylylsulphate 3′-phosphotransferase) has been isolated from Escherichia coli and from Saccharomyces cerevisiae. As major steps of purification, affinity chromatography on Sepharose CL 6B (“blue” or “red”) and chromatofocusing on polybuffer PBE 94tm were employed. The proteins were obtained in nearly homogeneous state after five chromatographic steps. The isolated enzymes from both sources appeared predominantly to exist as dimers. Upon reduction of the protein with dithiothreitol, it desintegrated into assumingly identical smaller subunits (E. coli rom Mr 90-85000 to 45-40000 and s. cerevisiae from 52-49500 to 28-29500). Both forms, dimer and monomer were found catalytically active. Preincubation of the isolated enzyme from either source in the presence of thioredoxin plus DTT, reduced glutathione or DTT increased the activity significantly. Treatment of the enzyme with SH-blocking reagents inactivated the enzyme irreversibly as compared to the inactivation caused by oxidants (2,6-dichlorophenol-indophenol, ferricyanide or oxydized glutathione). This oxidant induced inactivation was less pronounced for the fungal enzyme than for the bacterial protein. The enzyme from E. coli required thioredoxin in order to alleviate the GSSG-induced inactivation.
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    Effects of copper concentration in continuous culture on the aa 3-type cytochrome oxidase and respiratory chains of Paracoccus denitrificans (1989)
    Springer
    Archives of microbiology 151 (1989), S. 300-306 
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    ISSN: 1432-072X
    Keywords: Copper-limitation ; Escherichia coli ; Cytochrome oxidases ; Oxygen reduction ; Respiratory chains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role(s) of copper in a bacterial cytochrome oxidase of the aa 3-type was investigated by growth of Paracoccus denitrificans NCIB 8944, in batch and steady state continuous culture, in a medium from which the bulk of the copper had been extracted. In a medium containing approximately 0.02 μM copper, cellular copper content, cytochromes a+a 3 and cytochrome a 3 were reduced to 55%, 58% and 33% respectively of control values and there were also less marked decreases in cytochromes c+c 1 (to 85%) and a CO-binding b-type cytochrome, possibly cytochrome o (to 71%). Copper deficiency elicited in reduced minus oxidized difference spectra a shift to shorter wavelengths and narrowing of the band width of the α-band of the oxidase, and loss of a (negative) band near 830 nm attributable to CuA (the copper functionally associated with haem a in the oxidase complex). The oxidase in copper-deficient cells reacted with oxygen to form the oxy “Compound A” at rates similar to that in control cells but CO recombination to ferrous haem a 3 was slowed 4-fold in the copper deficient case. The results are interpreted as indicating loss of CuA and changes in the proportions of haems a and a 3 with retention of catalytic activity. Titrations of respiration rates with antimycin suggested that copper deficiency did not result in diversion of electron flux through an antimycin A-insensitive, cytochrome o-terminated branch of the respiratory chain.
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    Cloning and sequence of the mdh structural gene of Escherichia coli coding for malate dehydrogenase (1987)
    Springer
    Archives of microbiology 149 (1987), S. 36-42 
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    ISSN: 1432-072X
    Keywords: Catabolite repression ; Genetics ; Malate dehydrogenase ; Molecular cloning ; Sequence ; CRP binding site ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The malate dehydrogenase gene of Escherichia coli, which is susceptible to catabolite and anaerobic repression, has been cloned using plasmic pLC32-38 of Clarke and Carbon (1976). The nucleotide sequence was determined of a 2.47 kbp fragment, containing the mdh structural gene. All information necessary for expression of the mdh structural gene was mapped within a 1.3 kbp SphI-BstEII fragment. Compared with the untransformed wild type, transformations with pUC19 vector, containing this fragment, gave up to 40-fold more malate dehydrogenase activity in both E. coli wild type and mdh mutant recipients. Catabolite repression was not affected in the transformants. A possible CRP binding site in the promotor region of the mdh gene provides evidence for a co-regulation with fumA gene, the structural gene of fumarase, which is also subject to catabolite repression. The structures for transcription initiation and termination were similar to those previously described for E. coli. Amino acid sequence homologies between pro- and eucaryotic malate dehydrogenases are discussed.
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    The specific functions of menaquinone and demethylmenaquinone in anaerobic respiration with fumarate, dimethylsulfoxide, trimethylamine N-oxide and nitrate by Escherichia coli (1990)
    Springer
    Archives of microbiology 154 (1990), S. 60-66 
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    ISSN: 1432-072X
    Keywords: Menaquinone ; Demethylmenaquinone ; Anaerobic respiration ; Fumarate respiration ; DMSO respiration ; Nitrate respiration ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The respiratory activities of E. coli with H2 as donor and with nitrate, fumarate, dimethylsulfoxide (DMSO) or trimethylamine N-oxide (TMAO) as acceptor were measured using the membrane fraction of quinone deficient strains. The specific activities of the membrane fraction lacking naphthoquinones with fumarate, DMSO or TMAO amounted to ≤2% of those measured with the membrane fraction of the wild-type strain. After incorporation of vitamin K1 [instead of menaquinone (MK)] into the membrane fraction deficient of naphthoquinones, the activities with fumarate or DMSO were 92% or 17%, respectively, of the activities which could be theoretically achieved. Incorporation of demethylmenaquinone (DMK) did not lead to a stimulation of the activities of the mutant. In contrast, the electron transport activity with TMAO was stimulated by the incorporation of either vitamin K1 or DMK. Nitrate respiration was fully active in membrane fractions lacking either naphthoquinones or Q, but was ≤3% of the wild-type activity, when all quinones were missing. Nitrate respiration was stimulated on the incorporation of either vitamin K1 or Q into the membrane fraction lacking quinones, while the incorporation of DMK was without effect. These results suggest that MK is specifically involved in the electron transport chains catalyzing the reduction of fumarate or DMSO, while either MK or DMK serve as mediators in TMAO reduction. Nitrate respiration requires either Q or MK.
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    Some effects of growth conditions on steady state and heat shock induced htpG gene expression in continuous cultures of Escherichia coli (1990)
    Springer
    Archives of microbiology 155 (1990), S. 7-12 
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    ISSN: 1432-072X
    Keywords: Temperature ; Heat shock gene expression ; htpG ; Heat shock protein ; Escherichia coli ; Continuous culture ; Dilution rate ; Growth medium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Most of the data concerning heat shock gene expression reported in the literature are derived from batch culture experiments under substrate and nutrient sufficient conditions. Here, the effects of dilution rate and medium composition on the steady state and heat shock induced htpG gene expression have been investigated in continuous cultures of Escherichia coli, using a chromosomal htpG-lacZ gene fusion. During steady state growth temperature dependent patterns of the relative htpG expression were found to be largely similar, irrespective of the growth condition. However, nitrogen-limited growth resulted in a markedly reduced specific steady state htpG expression as compared to growth under carbon limitation or in complex medium, correlating qualitatively with the total cellular protein content. During heat shock, tight temperature controlled expression was evident. While the relative heat shock induced expression was largely identical at various dilution rates in a given growth medium, significantly different response patterns were observed in the three growth media at any give dilution rate. From these results a clearly temperature regulated htpG expression during both, steady and transient state growth in continuous culture is evident, which is further significantly affected by the growth condition used.
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    Ferrous iron dependent nitric oxide production in nitrate reducing cultures of Escherichia coli (1991)
    Springer
    Archives of microbiology 155 (1991), S. 341-347 
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    ISSN: 1432-072X
    Keywords: Chemodenitrification ; Nitric oxide ; Nitrous oxide ; Ferric iron reduction ; Ferrous iron oxidation ; Nitrate reduction ; Nitrite reduction ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract l-Lactate-driven ferric and nitrate reduction was studied in Escherichia coli E4. Ferric iron reduction activity in E. coli E4 was found to be constitutive. Contrary to nitrate, ferric iron could not be used as electron acceptor for growth. “Ferric iron reductase” activity of 9 nmol Fe2+ mg-1 protein min-1 could not be inhibited by inhibitors for the respiratory chain, like Rotenone, quinacrine, Actinomycin A, or potassium cyanide. Active cells and l-lactate-driven nitrate respiration in E. coli E4 leading to the production of nitrite, was reduced to about 20% of its maximum activity with 5 mM ferric iron, or to about 50% in presence of 5 mM ferrous iron. The inhibition was caused by nitric oxide formed by a purely chemical reduction of nitrite by ferrous iron. Nitric oxide was further chemically reduced by ferrous iron to nitrous oxide. With electron paramagnetic resonance spectroscopy, the presence of a free [Fe2+-NO] complex was shown. In presence of ferrous or ferric iron and l-lactate, nitrate was anaerobically converted to nitric oxide and nitrous oxide by the combined action of E. coli E4 and chemical reduction reactions (chemodenitrification).
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    URL: http://dx.doi.org/10.1007/BF00243453
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    Futile cycling of ammonium ions via the high affinity potassium uptake system (Kdp) of Escherichia coli (1991)
    Springer
    Archives of microbiology 155 (1991), S. 391-395 
    Details
    ISSN: 1432-072X
    Keywords: Potassium transport ; Ammonium transport ; Kdp ; Escherichia coli ; Futile cycling ; Chemostat culture ; Energy requirement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Escherichia coli Frag1 was grown under various nutrient limitations in chemostat culture at a fixed temperature, dilution rate and pH both in the presence and the absence of a high concentration of ammonium ions by using either ammonium chloride or dl-alanine as the sole nitrogen source. The presence of high concentrations of ammonium ions in the extracellular fluids of potassium-limited cultures of E. coli Frag1 caused an increase of the specific rate of oxygen consumption of these cultures. In contrast, under phosphate-, sulphate- or magnesium-limited growth conditions no such increase could be observed. The presence of high concentrations of ammonium ions in potassium-limited cultures of E. coli Frag5, a mutant strain of E. coli Frag1 which lacks the high affinity potassium uptake system (Kdp), did not increase the specific rate of oxygen consumption. These results indicate that ammonium ions, very similar to potassium ions both in charge and size, are transported via the K dp leading to a futile cycle of ammonium ions and ammonia molecules (plus protons) across the cytoplasmic membrane. Both the uptake of ammonium ions and the extrusion of protons would increase the energy requirement of the cells and therefore increase their specific rate of oxygen consumption. The involvement of a (methyl)ammonium transport system in this futile cycle could be excluded.
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    URL: http://dx.doi.org/10.1007/BF00243460
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  • 95
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    Prolonged environmental stress via a two step process selects mutants of Escherichia, Salmonella and Pseudomonas that grow at 54°C (1991)
    Springer
    Archives of microbiology 156 (1991), S. 307-311 
    Details
    ISSN: 1432-072X
    Keywords: Temperature ; Mutation ; Thermotolerance ; Escherichia coli ; Salmonella typhimurium ; Pseudomonas aeruginosoa ; DNA gyrase ; gyrA ; Nalidixic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A prolonged incubation of Escherichia, Salmonella or Pseudomonas at 48°C with nalidixic acid selected mutants (T48) able to grow at 48°C. A prolonged incubation at 54°C of the T48 mutants selected mutants (T54) able to grow at 54°C. These mutants were susceptible to the same bacteriophages as the original mesophilic strains. Auxotrophic phenotypes of Escherichia coli and Salmonella typhimurium mesophilic parents were demonstrated by these mutants if they were cultivated on minimal agar with cellobiose at 48°C or 54°C or on a minimal agar with glucose at 37°C. The T48 alleles mapped in the gyrA region of E. coli or S. typhimurium chromosome. In S. typhimurium the T54 alleles, which permit growth at 54°C, were shown by cotransductional analysis to be linked to gyrA.
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    URL: http://dx.doi.org/10.1007/BF00263003
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  • 96
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    The cis-acting DNA sequences required in vivo for bacteriophage Mu helper-mediated transposition and packaging (1990)
    Springer
    Archives of microbiology 154 (1990), S. 67-72 
    Details
    ISSN: 1432-072X
    Keywords: DNA transposition ; Virus encapsidation ; Phage Mu ; Cis-acting DNA sequences ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The 37,000 bp double-stranded DNA genome of bacteriophage Mu behaves as a plaque-forming transposable element of Escherichia coli. We have defined the cis-acting DNA sequences required in vivo for transposition and packaging of the viral genome by monitoring the transposition and maturation of Mu DNA-containing pSC101 and pBR322 plasmids with an induced helper Mu prophage to provide the trans-acting functions. We found that nucleotides 1 to 54 of the Mu left end define an essential domain for transposition, and that sequences between nucleotides 126 and 203, and between 203 and 1,699, define two auxiliary domains that stimulate transposition in vivo. At the right extremity, the essential sequences for transposition require not more than the first 62 base pairs (bp), although the presence of sequences between 63 and 117 bp from the right end increases the transposition frequency about 15-fold in our system. Finally, we have delineated the pac recognition site for DNA maturation to nucleotides 32 to 54 of the Mu left end which reside inside of the first transposase binding site (L1) located between nucleotides 1–30. Thus, the transposase binding site and packaging domains of bacteriophage Mu DNA can be separated into two well-defined regions which do not appear to overlap.
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    URL: http://dx.doi.org/10.1007/BF00249180
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  • 97
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    Effect of novel compound, 1-methyl-1-piperidino methane sulfonate (MPMS), on the osmoprotectant activity of glycine betaine, cholien and l-proline in Escherichia coli (1993)
    Springer
    Archives of microbiology 160 (1993), S. 81-86 
    Details
    ISSN: 1432-072X
    Keywords: Osmoprotectants ; Choline ; Proline ; Glycine betaine ; 1-Methyl-1-piperidino methane sulfonate (MPMS) ; Transport ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A novel compound, 1-methyl-1-piperidino methane sulfonate (MPMS), was found to block the osmoprotectant activity of choline and L-proline, but not glycine betaine in Escherichia coli. MPMS was more active against salt-sensitive than salt-resistant strains, but had no effect on the salt tolerance of a mutant which was unable to transport choline, glycine betaine and proline. Growth of E. coli in NaCl was inhibited by MPMS and restored by glycine betaine, but not by choline or L-proline. Uptake of radiolabeled glycine betaine, choline or L-proline by cells grown at high osmolarity was not inhibited when MPMS and the radioactive substrates were added simultaneously. Preincubation for 5 min with MPMS reduced the uptake of choline and L-proline, but not glycine betaine. Similar incubation with MPMS had no effect on the uptake of radiolabeled glucose or succinate. The toxicity of MPMS was much lower than that of the L-proline analogues L-azetidine-2-carboxylic acid and 3,4-dehydro-DL-proline. The exact mechanism by which MPMS exerts its effect is not entirely clear. MPMS or a metabolite may interfere with the activity of several independent permeases involved in the uptake of osmoprotective compounds, or the conversion of choline to glycine betaine, or effect the expression of some of the osmoregulatory genes.
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    URL: http://dx.doi.org/10.1007/BF00288707
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  • 98
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    The gluEMP operon from Zymomonas mobilis encodes a high-affinity glutamate carrier with similiarity to binding-protein-dependent transport systems (1996)
    Springer
    Archives of microbiology 165 (1996), S. 325-332 
    Details
    ISSN: 1432-072X
    Keywords: Key wordsZymomonas mobilis ; Escherichia coli ; Glutamate transport ; Binding-protein-dependent ; transport ; Grp ; Glutamate uptake regulatory protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nucleotide sequence downstream of the grp gene, encoding the glutamate uptake regulatory protein of Zymomonas mobilis, was determined. Three clustered genes (gluE, gluM, and gluP) close to ghe grp gene, but on the opposite strand, were identified. These genes encode a high-affinity transport system for glutamate and aspartate. The gluP gene product is a polypeptide of 25.4 kDa and contains segments with significant similiarity to the ATP-binding proteins of binding-protein-dependent transport systems. The GluM polypeptide (22.9 kDa) is highly hydrophobic and consists of four potential membrane-spanning domains. The hydrophilic gluE gene product, with a molecular mass of 22.1 kDa, contains a region with sequence similiarity to some of the periplasmic binding proteins and a sequence motif of a signal peptide for periplasmic localization. The transport system could not be functionally expressed in Z. mobilis. However, when heterologously expressed in Escherichia coli, it catalyzed uptake of glutamate, which was characterized kinetically. Our results suggest that the glutamate transport system encoded by the gluEMP operon is repressed in Z. mobilis by the regulatory protein Grp.
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    URL: http://dx.doi.org/10.1007/s002030050334
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  • 99
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    Functional 70S hybrid ribosomes from blue-green algae and bacteria (1976)
    Springer
    Archives of microbiology 109 (1976), S. 95-99 
    Details
    ISSN: 1432-072X
    Keywords: Anacystis nidulans ; Escherichia coli ; Hybrid ribosomes ; Ribosomes ; Procaryotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hybrid 70S ribosomes were produced by combining Anacystis nidulans and Escherichia coli 30S and 50S subunits. Both the A. nidulans 30S-E. coli 50S and E. coli 30S- A. nidulans 50S hybrids were functional in synthesizing protein when tested in a standard in vitro amino acid incorporating system. Both 70S hybrids were inhibited by streptomycin but the degree of inhibition was dependent upon the source of the 30S subunit. The ability to form functional 70S ribosomes from subunits of blue-green algae and bacteria is further evidence of the procaryotic nature of blue-greens and of the functional homology of the two protein synthesizing systems.
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    URL: http://dx.doi.org/10.1007/BF00425118
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  • 100
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    Pole cap formation in Escherichia coli following induction of the maltose-binding protein (1978)
    Springer
    Archives of microbiology 118 (1978), S. 207-218 
    Details
    ISSN: 1432-072X
    Keywords: Periplasm ; Maltose-binding protein ; Maltose transport ; Cell division ; Pole caps ; Cell envelope ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract After induction with maltose, 30–40% of the total protein in the osmotic shock fluid consist of maltose-binding protein while the induction ratio (maltose versus glycerol grown cells) for the amount of binding protein synthesized as well as for maltose transport is in the order of 10. Induction of maltose transport does not occur during all times of the cell cycle, but only shortly before cell division. Electronmicroscopic analysis of cells grown logarithmically on glycerol or maltose revealed in the latter the formation of large pole caps. These pole caps arise from an enlargement of the periplasmic space. Small cells contain one pole cap, large cells contain two. Pulse label studies with strain BUG-6, a mutant that is temperature sensitive for cell division reveal the following: Growth at the non-permissive temperature prevents maltose-binding protein synthesis and formation of new transport capacity. After shifting to the permissive temperature the cells regain both functions. Simultaneously, the newly formed cells exhibit pole caps. We conclude that the induction of maltose-binding protein is responsible for the formation of pole caps. In addition, beside the presence of inducer, cell cycle events occuring during division are necessary for the synthesis of maltose-binding protein.
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    URL: http://dx.doi.org/10.1007/BF00415731
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