ABSTRACT
Four strains of gram-negative, anaerobic, non-spore-forming bacteria that were curved rods which were motile by means of flagella originating from the concave side of the cells and which fermented succinate quantitatively to propionate were isolated from high dilutions of rumen ingesta obtained from cows on pasture. The bacteria were asaccharolytic and not proteolytic and did not ferment amino acids or peptides. Succinate was the only substrate fermented. Rumen fluid together with yeast extract was required for good growth on succinate. Growth on succinate was enhanced in the presence of fumarate. The strains did not grow at 22 degrees C, and growth at 45 degrees C was in all cases less than growth at 39 degrees C. The cellular fatty acid compositions of all four strains were determined. The DNA base composition was about 46 mol% G + C. The complete 16S ribosomal DNA sequence of the type strain (strain S1-1) was determined, and the phylogenetic relationships were analyzed. The most closely related genera were the genera Selenomonas, Zymophilus, and Pectinatus, whereas the recently described succinate-fermenting organism Succiniclasticum ruminis was distantly related. The name proposed for these strains is Schwartzia succinivorans gen. nov., sp. nov.; the type strain is strain S1-1 (= DSM 10502). These organisms are common inhabitants of the rumina of cows on pasture.
Subject(s)
Gram-Negative Anaerobic Bacteria/classification , Gram-Negative Anaerobic Bacteria/metabolism , Rumen/microbiology , Succinates/metabolism , Amino Acids/metabolism , Animals , Base Composition , Cattle , Fatty Acids/analysis , Fermentation , Flagella , Fumarates/metabolism , Gram-Negative Anaerobic Bacteria/chemistry , Gram-Negative Anaerobic Bacteria/growth & development , Molecular Sequence Data , Peptides/metabolism , Phylogeny , RNA, Ribosomal, 16S/genetics , Yeasts/metabolismABSTRACT
A gram-negative, anaerobic, nonmotile, non-spore-forming, rod-shaped bacterium that fermented succinate quantitatively to propionate was isolated from a high dilution of rumen ingesta obtained from a dairy cow fed a production diet containing grass silage as the main roughage source. This organism did not grow on any of the following energy sources: 12 carbohydrates, pyruvate, lactate, 7 dicarboxylic acids, aspartate, citrate, and trans-aconitate. Both rumen fluid and yeast extract were necessary for good growth on succinate. The organism was negative for the following characteristics: production of propionate from threonine, protein digestion, sulfide production, nitrate reduction, catalase activity, and urease activity. There was no growth at 22 degrees C and reduced growth at 45 degrees C compared with growth at 39 degrees C. The DNA base composition was 52 mol% G + C. The complete 16S rRNA sequence (EMBL accession number, X81137) was obtained, and the phylogenetic relationships of the organism were determined. The most closely related genera were the genera Acidaminococcus and Phascolarctobacterium. The name proposed for this bacterium is Succiniclasticum ruminis gen. nov., sp. nov.; the type strain is strain SE10 (= DSM 9236). Additional isolation attempts revealed that S. ruminis is a common inhabitant of the rumina of cows that are fed production diets and of cows on pasture.
Subject(s)
Gram-Negative Anaerobic Bacteria/classification , Propionates/metabolism , Rumen/microbiology , Succinates/metabolism , Animals , Cattle , DNA, Bacterial/genetics , Energy Metabolism , Gram-Negative Anaerobic Bacteria/metabolism , Molecular Sequence Data , Phylogeny , RNA, Bacterial/genetics , RNA, Ribosomal, 16S/geneticsABSTRACT
A new Gram-negative, non-sporulating, rod-shaped, anaerobic bacterium capable of fermenting cellulose and starch was isolated from the rumens of sheep fed supplemented maize stover diets. The organism fermented few carbohydrates, showing a preference for polysaccharides. The main acid products of carbohydrate fermentation were butyrate and formate. Acetate was utilized.
Subject(s)
Fusobacterium/metabolism , Rumen/microbiology , Anaerobiosis , Animals , Butyrates/metabolism , Cellulose/metabolism , Culture Media , Fermentation , Formates/metabolism , Fusobacterium/growth & development , Fusobacterium/ultrastructure , Microscopy, Electron , Sheep , Starch/metabolismABSTRACT
Phosphoenolpyruvate carboxykinase (adenosine 5'-triphosphate) was the only enzyme capable of carboxylating pyruvate or phosphoenolpyruvate that could be demonstrated in sonicated cells or cell-free extracts of a group 1 butyrivibrio.
ABSTRACT
The growth responses of an acetate-utilizing isolate of Butyrivibrio fibrisolvens to CO2, acetate and pyruvate were determined using a chemically-defined medium. Carbon dioxide was essential for growth and both acetate and pyruvate increased growth. 14C from [I-14C]pyruvate appeared predominantly in formate and lactate. These results, together with those obtained with enzyme preparations, indicated pyruvate synthase, pyruvate-CO2 exchange and pyruvate formate lyase to be active.
