Fermentative degradation of putrescine by new strictly anaerobic bacteria
ABSTRACT Three strains of new strictly anaerobic, Grampositive, non-sporeforming bacteria were isolated from various anoxic sediment samples with putrescine as sole carbon and energy source. Optimal growth in carbonate-buffered defined medium occurred at 37~ at pH 7.2-7.6. The DNA base ratio of strain NorPutl was 29.6 _+ 1 mol% guanine plus cytosine. In addition to a surface layer and the eptidoglycan layer, the cell wall contained a second innermost layer with a periodic arrangement of subunits. All strains fermented putrescine to acetate, butyrate, and molecular hydrogen; the latter originated from both oxidative putrescine deamination and 4-aminobutyraldehyde oxidation. In defined mixed cultures with methanogens or homoacetogenic bacteria, methane or additional acetate were formed due to interspecies hydrogen transfer. Also 4-aminobutyrate and 4-hydroxybutyrate were fermented to acetate and butyrate, but no hydrogen was released from these substrates. No sugars, organic acids, other primary amines or amino acids were used as substrates. Neither sulfate, thiosulfate, sulfur, nitrate nor fumarate was reduced. Most of the enzymes involved in putrescine degradation could be demonstrated in cell-free extracts. A pathway of putrescine fermentation via 4-aminobutyrate and crotonyl- CoA with subsequent dismutation to acetate and butyrate is suggested.
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ABSTRACT: The strictly anaerobic, gram-positive, non-spore-forming bacterium strain NorPut1T ferments putrescine to acetate, butyrate, molecular hydrogen and ammonia. It also utilizes 4-aminobutyrate and 4-hydroxybutyrate as growth substrates. Comparative 16S rDNA sequence analysis confirmed a phylogenetic affiliation of this strain to the phylum of gram-positive bacteria with low DNA G+C content. Together with its closest relative, 'Clostridium aminobutyricum' (DSM 2634), and several Eubacterium species, strain NorPut1T represents a well-defined monophyletic group. Moderate overall 16S rRNA sequence similarities (< 91%) were found for the NorPut1T/'Clostridium aminobutyricum' pair and several Eubacterium species. The type species, Eubacterium limosum, is not a member of the group and, together with Eubacterium barkeri and Pseudoramibacter alactolyticus, represents a distant phylogentic cluster. Therefore, a new genus, Anaerovorax, is proposed as harbouring strain NorPut1T (= DSM 5092T), which is described as a new species, i.e. Anaerovorax odorimutans.International Journal of Systematic and Evolutionary Microbiology 07/2000; 50 Pt 4:1591-4. DOI:10.1099/00207713-50-4-1591 · 2.80 Impact Factor
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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.Archives of Microbiology 09/1992; DOI:10.1007/BF00245360 · 1.86 Impact Factor
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ABSTRACT: Anaerobic growth of Escherichia coli was studied with glycerol as electron source and a three-electrode poised-potential system with potassium ferricyanide as mediator. Similar to fumarate, potassium ferricyanide was used as electron acceptor in batch-culture experiments. In experiments with regulated electrodes, glycerol was degraded completely, and an electron flow of 3.0 to 4.0 mA was obtained. The electron balances were in the range of 98%-107%, and a growth rate of 0.095 h -1 was calculated. These results are discussed with respect to the energetics of iron reduction by E. coli and by other bacteria.Applied Microbiology and Biotechnology 12/1989; DOI:10.1007/BF00165883 · 3.81 Impact Factor