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  • 1
    Electronic Resource
    Electronic Resource
    A complete citric acid cycle in assimilatory metabolism of Pelobacter acidigallici, a strictly anaerobic, fermenting bacterium (1990)
    Springer
    Archives of microbiology 154 (1990), S. 394-399 
    Details
    ISSN: 1432-072X
    Keywords: Trihydroxygenzenes ; Anabolism ; Anaerobic citric acid cycle ; Succinyl-CoA: acetoacetate CoA transferase ; Phylogeny ; Gram-negative bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pelobacter acidigallici is a strictly anaerobic bacterium that ferments trihydroxybenzenes to 3 mol acetate/mol substrate. The key intermediate linking the catabolic sequences to the formation of cell matter is acetyl-CoA. Since P. acidigallici is independent of further external electron donors, it must oxidize part of the acetyl-CoA to provide reducing equivalents for anabolism. In this study we demonstrate the presence of all enzymes necessary to operate a modified citric acid cycle, with activities sufficient to support growth. Unusual enzymes in the cycle are 2-oxoglutarate synthase and succinyl-CoA: acetoacetate CoA transferase. Anaplerotic reactions are catalyzed by pyruvate synthase, PEP synthetase and PEP carboxylase. No CO dehydrogenase, hydrogenase, or formate dehydrogenase activity could be detected. The phylogenetic implications of these findings with respect to the relatedness of P. acidigallici to gramnegative, sulfur-reducing bacteria by 16 S rRNA cataloguing are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00276537
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  • 2
    Electronic Resource
    Electronic Resource
    A strictly anaerobic nitrate-reducing bacterium growing with resorcinol and other aromatic compounds (1992)
    Springer
    Archives of microbiology 158 (1992), S. 48-53 
    Details
    ISSN: 1432-072X
    Keywords: Obligate nitrate reducer ; Resorcinol hydrolysis ; Aromatic compounds ; Alcaligenes denitrificans ; Anaerobic degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract With resorcinol as sole source of energy and organic carbon, two stains of gram-negative, nitrate-reducing bacteria were isolated under strictly anaerobic conditions. Strain LuBRes1 was facultatively anaerobic and catalase- and superoxide dismutase-positive. This strain was affiliated with Alcaligenes denitrificans on the basis of substrate utilization spectrum and peritrichous flagellation. Strain LuFRes1 could grow only under anaerobic conditions with oxidized nitrogen compounds as electron acceptor. Cells were catalase-negative but superoxide dismutase-positive. Since this strain was apparently an obligate nitrate reducer, it could not be grouped with any existing genus. Resorcinol was completely oxidized to CO2 by both strains. Neither an enzyme activity reducing or hydrolyzing the resorcinol molecule, nor an acyl-CoA-synthetase activating resorcylic acids or benzoate was detected in cell-free extracts of cells grown with resorcinol. In dense cell suspensions, both strains produced a compound which was identified as 5-oxo-2-hexenoic acid by mass spectrometric analysis. This would indicate a direct, hydrolytic cleavage of the resorcinol nucleus without initial reduction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249065
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  • 3
    Electronic Resource
    Electronic Resource
    Anaerobic degradation of hydroaromatic compounds by newly isolated fermenting bacteria (1992)
    Springer
    Archives of microbiology 158 (1992), S. 320-327 
    Details
    ISSN: 1432-072X
    Keywords: Anaerobic degradation ; Hydroaromatic compounds ; Quinic acid ; Shikimic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aerobic organisms degrade hydroaromatic compounds via the hydroaromatic pathway yielding protocatechuic acid which is further metabolized by oxygenase-mediated ring fission in the 3-oxoadipate pathway. No information exists on anaerobic degradation of hydroaromatics so far. We enriched and isolated from various sources of anoxic sediments several strains of rapidly growing gram-negative bacteria fermenting quinic (1,3,4,5-tetrahydroxy-cyclohexane-1-carboxylic acid) and shikimic acid (3,4,5-trihydroxy-1-cyclohexene-1-carboxylic acid) in the absence of external electron acceptors. Quinic and shikimic acid were the only ones utilized of more than 30 substrates tested. The marine isolates formed acetate, butyrate, and H2, whereas all freshwater strains formed acetate and propionate as typical fermentation products. Aromatic intermediates were not involved in this degradation. Characterization of the isolates, fermentation balances for both hydroaromatic compounds, and enzyme activities involved in one degradation pathway are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00245360
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  • 4
    Electronic Resource
    Electronic Resource
    Phloroglucinol pathway in the strictly anaerobic Pelobacter acidigallici: fermentation of trihydroxybenzenes to acetate via triacetic acid (1992)
    Springer
    Archives of microbiology 157 (1992), S. 417-424 
    Details
    ISSN: 1432-072X
    Keywords: Trihydroxybenzenes ; Anaerobic degradation ; Aromatic compounds ; Phloroglucinol pathway ; Ring cleavage ; 3-Hydroxy-5-oxohexanoic acid ; Beta-oxidation ; Triacetic acid (3,5-dioxohexanoic acid) ; Pelobacter acidigallici
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The strictly anaerobic, fermenting bacterium Pelobacter acidigallici degrades several trihydroxybenzene derivatives to stoichiometric amounts of acetate. We now report on the enzymatic activities in cell extracts which are responsible for the fermentative degradation of these aromatic compounds, and postulate a novel phloroglucinol pathway involving triacetic acid as an unusual metabolic intermediate. Gallate is decarboxylated to pyrogallol by a specific, Mg2+-dependent, soluble enzyme activity, followed by conversion of pyrogallol to phloroglucinol, involving an unusual intermolecular transhydroxylation described previously. Phloroglucinol is then reduced to dihydrophloroglucinol (5-hydroxy-1,3-cyclohexanedione) by an NADPH-dependent phloroglucinol reductase. Dihydrophloroglucinol is cleaved hydrolytically to 3-hydroxy-5-oxohexanoic acid, which is then oxidized to triacetic acid (3,5-dioxohexanoic acid) by a unique, NADP+-dependent dehydrogenase. Triacetic acid is activated by CoA transfer from acetyl-CoA, and then converted to 3 acetyl-CoA by two subsequent β-ketothiolase reactions. ATP is generated via phosphotransacetylase and acetate kinase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249098
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  • 5
    Electronic Resource
    Electronic Resource
    Anaerobic and aerobic oxidation of ferrous iron at neutral pH by chemoheterotrophic nitrate-reducing bacteria (1998)
    Springer
    Archives of microbiology 169 (1998), S. 159-165 
    Details
    ISSN: 1432-072X
    Keywords: Key words Iron oxidation ; Ferrous iron ; Ferric iron ; Nitrate reduction ; Sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nine out of ten anaerobic enrichment cultures inoculated with sediment samples from various freshwater, brackish-water, and marine sediments exhibited ferrous iron oxidation in mineral media with nitrate and an organic cosubstrate at pH 7.2 and 30° C. Anaerobic nitrate-dependent ferrous iron oxidation was a biological process. One strain isolated from brackish-water sediment (strain HidR2, a motile, nonsporeforming, gram-negative rod) was chosen for further investigation of ferrous iron oxidation in the presence of acetate as cosubstrate. Strain HidR2 oxidized between 0.7 and 4.9 mM ferrous iron aerobically and anaerobically at pH 7.2 and 30° C in the presence of small amounts of acetate (between 0.2 and 1.1 mM). The strain gained energy for growth from anaerobic ferrous iron oxidation with nitrate, and the ratio of iron oxidized to acetate provided was constant at limiting acetate supply. The ability to oxidize ferrous iron anaerobically with nitrate at approximately pH 7 appears to be a widespread capacity among mesophilic denitrifying bacteria. Since nitrate-dependent iron oxidation closes the iron cycle within the anoxic zone of sediments and aerobic iron oxidation enhances the reoxidation of ferrous to ferric iron in the oxic zone, both processes increase the importance of iron as a transient electron carrier in the turnover of organic matter in natural sediments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050555
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  • 6
    Electronic Resource
    Electronic Resource
    Degradation of hydroxyhydroquinone by the strictly anaerobic fermenting bacterium Pelobacter massiliensis sp. nov. (1991)
    Springer
    Archives of microbiology 155 (1991), S. 511-516 
    Details
    ISSN: 1432-072X
    Keywords: Hydroxyhydroquinone ; Anaerobic degradation ; Pelobacter massiliensis sp. nov. ; Trihydroxybenzenes ; Aromatic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new rod-shaped, gram-negative, non-sporeforming, strictly anaerobic bacterium (strain HHQ7) was enriched and isolated from marine mud samples with hydroxyhydroquinone (1,2,4-trihydroxybenzene) as sole substrate. Strain HHQ7 fermented hydroxyhydroquinone, pyrogallol (1,2,3-trihydroxybenzene), phloroglucinol (1,3,5-trihydroxybenzene) and gallic acid (3,4,5-trihydroxybenzoate) to 3 mol acetate (plus 1 mol CO2 in the case of gallic acid) per mol of substrate. Resorcinol accumulated intermediately during growth on hydroxy-hydroquinone. No other aliphatic or aromatic substrates were utilized. Sulfate, sulfite, sulfur, nitrate, and fumarate were not reduced with hydroxyhydroquinone as electron donor. The strain grew in sulfide-reduced mineral medium supplemented with 7 vitamins. The DNA base ratio was 59% G+C. Strain HHQ7 is classified as a new species of the genus Pelobacter, P. massiliensis. Experiments with dense cell suspensions of hydroxyhydroquinone-and pyrogallol-grown cells showed different kinetics of hydroxyhydroquinone and pyrogallol degradation, as well as different patterns of resorcinol accumulation, indicating that these substrates are metabolized by different transhydroxylation reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00244971
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  • 7
    Electronic Resource
    Electronic Resource
    Anaerobic degradation of 3-hydroxybenzoate by a newly isolated nitrate-reducing bacterium (1991)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 84 (1991), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract A gram-negative nitrate-reducing bacterium, strain Asl-3, was isolated from activated sludge with nitrate and 3-hydroxybenzoate as sole source of carbon and energy. The new isolate was faculaatively anaerobic, catalase- and oxidase-positive and polarly monotrichously flagellated. In addition to nitrate, nitrite, N2O, and O2 served as electron acceptors. Growth with 3-hydroxybenzoate and nitrate was biphasic: nitrate was completely reduced to nitrite before nitrite reduction to N2 started. Benzoate, 3-hydroxybenzoate, 4-hydroxybenzoate, protocatechuate or phenyl-acetate served as electron and carbon source under aerobic and anaerobic conditions. During growth with excess carbon source, poly-β-hydroxybutyrate was formed. These characteristics allow the affiliation of strain Asl-3 with the family Pseudomonadaceae. Analogous to the pathway of 4-hydroxybenzoate degradation in other bacteria, the initial step in anaerobic 3-hydroxybenzoate degradation by this organism was activation to 3-hydroxy-benzoyl-CoA in an ATP-consuming reaction. Cell extracts of 3-hydroxybenzoate-grown cells exhibited 3-hydroxybenzoyl-CoA synthetase activity of 190 nmol min−1 mg protein−1 as well as benzoyl-CoA synthetase activity of 86 nmol min−1 mg protein−1. A reductive dehydroxylation of 3-hydroxybenzoyl-CoA could not be demonstrated due to rapid hydrolysis of chemically synthesized 3-hydroxybenzoyl-CoA by cell extracts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1991.tb04608.x
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  • 8
    Electronic Resource
    Electronic Resource
    Preferential cultivation of type II methanotrophic bacteria from littoral sediments (Lake Constance) (2004)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 47 (2004), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Most widely used medium for cultivation of methanotrophic bacteria from various environments is that proposed in 1970 by Whittenbury. In order to adapt and optimize medium for culturing of methanotrophs from freshwater sediment, media with varying concentrations of substrates, phosphate, nitrate, and other mineral salts were used to enumerate methanotrophs by the most probable number method. High concentrations (〉1 mM) of magnesium and sulfate, and high concentrations of nitrate (〉500 μM) significantly reduced the number of cultured methanotrophs, whereas phosphate in the range of 15–1500 μM had no influence. Also oxygen and carbon dioxide influenced the culturing efficiency, with an optimal mixing ratio of 17% O2 and 3% CO2; the mixing ratio of methane (6–32%) had no effect. A clone library of pmoA genes amplified by PCR from DNA extracted from sediment revealed the presence of both type I and type II methanotrophs. Nonetheless, the cultivation of methanotrophs, also with the improved medium, clearly favored growth of type II methanotrophs of the Methylosinus/Methylocystis group. Although significantly more methanotrophs could be cultured with the modified medium, their diversity did not mirror the diversity of methanotrophs in the sediment sample detected by molecular biology method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0168-6496(03)00260-5
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  • 9
    Electronic Resource
    Electronic Resource
    In vivo observation of conidial germination at the oxic–anoxic interface and infection of submerged reed roots by Microdochium bolleyi (2003)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 45 (2003), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The underground plant parts of reed (Phragmites australis) growing in anoxic soil of the littoral zone of lakes are provided with oxygen via an aerenchyma. Some of this oxygen is released into the rhizosphere, which creates a potential microhabitat for aerobic fungi. Although fungal endophytes of reed have been shown to occur also in roots of flooded habitats, it is not known whether or how fungi can infect roots growing in anoxic or hypoxic soil. To study fungal infection of reed roots in the laboratory, we developed an incubation chamber to expose reed roots to conidia of Microdochium bolleyi in an anoxic agar medium and to observe fungal infection in vivo. Germination rates of conidia were high close to living roots, but decreased to zero in anoxic areas of the chamber. Conidial germ tubes located up to 200 μm from the roots grew preferentially towards the living roots. Conidia also germinated close to air-filled Teflon tubes and exhibited germ-tube tropism, but not as distinctly as on living reed roots. Conidia did not germinate in the neighbourhood of dead roots in anoxic agar. However, in the aerated margin of the incubation chamber most conidia germinated and exhibited tropic growth towards dead roots. Penetration of M. bolleyi through several cell layers of living roots was observed in cryo-microtome sections. Penetration was significantly deeper with illuminated plants than with plants kept in the dark; in some cases even the stele was reached. This is the first observation of oxygen released from roots to support growth of an aerobic fungus and of fungal penetration into root tissue in an anoxic environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0168-6496(03)00161-2
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  • 10
    Electronic Resource
    Electronic Resource
    Microbiology Woodworker's digest (2007)
    [s.l.] : Nature Publishing Group
    Nature 450 (2007), S. 487-488 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The gut of wood-feeding termites is a tiny but astonishingly efficient bioreactor, in which microbes catalyse the conversion of lignified plant cell walls to fermentation products that drive the metabolism of their host. Molecular phylogenetic data have revealed the presence of hundreds of ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/450487a
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