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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 243 (2005), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We determined almost complete nifH and nifD genes from representatives of all recognized genera of heliobacteria, the strictly anaerobic phototrophs belonging to the low GC gram-positive bacteria. The heliobacterial sequences formed a highly supported monophyletic group that is clearly distinct from any known diazotrophs, in both NifH and NifD trees. According to the classification of nitrogenase genes in four major clusters, the clade of heliobacterial sequences belonged to cluster I and did not cluster with any of the Clostridium (cluster III) or Paenibacillus (cluster I) species, the close neighbors of heliobacteria based on the 16S rRNA phylogeny. One partial anfH or alternative nitrogenase sequence was detected from Heliobacterium gestii. Although Heliophilum fasciatum is known to fix nitrogen based on the acetylene reduction test, nifH and/or nifD genes were not detected by either the PCR amplification or Southern hybridization methods.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 721 (1994), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
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  • 3
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Partial nucleotide sequences (120 bp) of the 16S rRNA gene (rDNA) containing a variable α region were compared in 89 strains of the genus Streptomyces belonging to eight major clusters of category I in Bergey's Manual of Systematic Bacteriology. Fifty-seven kinds of partial 16S rDNA sequences were observed among the 89 strains. Forty-three of the strains were grouped into 11 ‘identity groups’, based on the fact that the strains in each group shared an identical sequence in the 120-bp region. The results of a phylogenetic analysis based on the 16S rDNA 120-bp sequences revealed that 60 of the 89 strains could be categorized into seven clusters, each consisting of four or more strains. Based on these observations it was concluded that short nucleotide sequences bearing the variable α region are useful for Streptomyces species identification.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 150 (1997), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A putative nicking site in the double strand origin (DSO) of the Streptomyces plasmid pSN22 was identified by comparing the nucleotide sequence of the DSO region with those of two other Streptomyces plasmids, pIJ101 and pJV1. A 7-bp sequence of this putative nicking site, 5′-CTTGGGA-3′, was similar to the consensus sequence of the nicking site of the pC194 group of plasmids. When several point mutations were introduced into this 7-bp sequence, the transformation abilities of the mutant plasmid molecules for Streptomyces lividans were either reduced or lost. Southern hybridization analysis indicated that these mutant plasmids could not replicate in S. lividans, but were integrated into the chromosomal DNA.
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  • 5
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The traB gene on the Streptomyces conjugative plasmid pSN22 is required for intermycelial plasmid transfer and the mobilization of chromosomal markers (Cma). The predicted amino acid sequence of TraB contains one Walker type-A and two type-B NTP-binding motifs. Site-directed mutagenesis revealed that the type-A motif and one of the type-B motifs, 109 amino acid residues downstream of the type-A motif, were essential for both plasmid transfer and Cma. The second type-B sequence could be changed without any phenotypic effect. A modified traB gene was constructed, resulting in the production of a functional protein with an amino-terminal c-Myc epitope tag for immunological analysis. This protein was associated with the cytoplasmic membrane, suggesting that TraB is a membrane protein that uses energy from ATP hydrolysis to transport DNA between mycelia. The c-Myc tagging of TraB decreased the efficiency of intramycelial plasmid spread, suggesting that TraB is involved in both inter- and intramycelial transfer processes.
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  • 6
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Mutants of xylose-assimilating recombinant Saccharomyces cerevisiae carrying the xylose reductase and xylitol dehydrogenase genes on plasmid pEXGD8 were selected, after ethyl methanesulfonate treatment, for their rapid growth on xylose medium. The fastest growing strain (strain IM2) showed a lower activity of xylose reductase but a higher ratio of xylitol dehydrogenase to xylose reductase activities than the parent strain, as well as high xylulokinase activity. Southern hybridization of the chromosomal DNA indicated that plasmid pEXGD8 was integrated into the chromosome of mutant IM2, resulting in an increase in the stability of the cloned genes. In batch fermentation under O2 limitation, the yield and production rate of ethanol were improved 1.6 and 2.7 times, respectively, compared to the parent strain. In fed-batch culture with slow feeding of xylose and appropriate O2 supply at a low level, xylitol excreted from the cells was limited and the ethanol yield increased 1.5 times over that in the batch culture, with a high initial concentration of xylose, although the production rate was reduced. The results suggested that slow conversion of xylose to xylitol led to a lower level of intracellular xylitol, resulting in less excretion of xylitol, and an increase in the ethanol yield. It was also observed that the oxidation of xylitol was strongly affected by the O2 supply.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 22 (1985), S. 336-342 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The genepheA + coding chorismate niutase P-prephenate dehydratase, one of the regulatory enzymes of phenylalanine biosynthesis, was cloned into the down-stream of PR-PL tandem promoter. In this construction, both the native promoter-operator region and the attenuator region ofpheA + operon were eliminated so as to avoid the repression and attenuation ofpheA + gene expression. The expression ofpheA + gene was directed by PR-PL tandem promoter of bacteriophage lambda and controlled by a temperature sensitive repressor, cI857. It was shown that the expression as well as phenylalanine production was regulated by temperature. Maximum production of phenylalanine, 170 mg/l, was obtained at 40°C. The host strain, MC1065, produced a trace (4 mg/l) of phenylalanine at the same temperature.
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  • 8
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract. Mutants of xylose-assimilating recombinant Saccharomyces cerevisiae carrying the xylose reductase and xylitol dehydrogenase genes on plasmid pEXGD8 were selected, after ethyl methanesulfonate treatment, for their rapid growth on xylose medium. The fastest growing strain (strain IM2) showed a lower activity of xylose reductase but a higher ratio of xylitol dehydrogenase to xylose reductase activities than the parent strain, as well as high xylulokinase activity. Southern hybridization of the chromosomal DNA indicated that plasmid pEXGD8 was integrated into the chromosome of mutant IM2, resulting in an increase in the stability of the cloned genes. In batch fermentation under O2 limitation, the yield and production rate of ethanol were improved 1.6 and 2.7 times, respectively, compared to the parent strain. In fed-batch culture with slow feeding of xylose and appropriate O2 supply at a low level, xylitol excreted from the cells was limited and the ethanol yield increased 1.5 times over that in the batch culture, with a high initial concentration of xylose, although the production rate was reduced. The results suggested that slow conversion of xylose to xylitol led to a lower level of intracellular xylitol, resulting in less excretion of xylitol, and an increase in the ethanol yield. It was also observed that the oxidation of xylitol was strongly affected by the O2 supply.
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  • 9
    ISSN: 0006-3592
    Keywords: rheology ; Perilla frutescens ; plant cell culture ; cell suspension ; bingham fluid ; morphology ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Physical properties such as viscosity, fluid dynamic behavior of cell suspension, and size distribution of cell aggregates of a plant, Perilla frustescens, cultured in a liquid medium were studied. As a result of investigations using cells harvester after 12 days of cultivation in a flask, it was found that the apparent viscosity of the cell suspension did not change with any variation of cell concentration below 5 g dry cell/L but markedly increased when the cell concentration increased over 12.8 g dry cell/L. The cell suspension exhibited the characteristics of a Bingham plastic fluid with a small yield stres. The size of cell aggregates in the range 74 to 500 μm did not influence the rheological characteristics of the cell suspension. The rheological characteristics of cultivation mixtures of P. frutescens cultivated in a flask and in a bioreactor were also investigated. The results showed that the flow characteristics of the cell culture could be described by a Bingham plastic model. At the later stage of cultivation, the apparent viscosity increased steadily, even though the biomass concentration (by dry weight) decreased, due to the increase of individual cell size. © 1992 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 649-654 
    ISSN: 0006-3592
    Keywords: anthocyanin production ; bioreactor cultivation ; Perilla frutescens ; plant cell culture ; shear effects ; metabolism ; secondary ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The short-time effects of shear on suspended cells of Perilla frutescens were quantitatively analyzed by exposing the cells to a well-defined flow field in a rotating drum reactor. It was found that both shear rate and shearing time significantly affected cell viability. The quantitative effects of shear on cell growth and the production of anthocyanin, a secondary metabolite, by the cell cultures were further investigated in a series of batch cultivations using a 5-L plant cell bioreactor with a marine impeller. The results indicated that there was an optimum range of shear rate; i.e., an average shear rate of 20 to 30 s-1 or an impeller tip speed of 5 to 8 dm/s, which maximized all the values of the following parameters: the specific growth rate, the maximum cell concentration, the (specific) production and productivity of anthocyanin, and the cell and anthocyanin yields. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
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