valericigenes and related environmental samples, although there is no type strain for the type selleck species Oscillospira guilliermondii. Accordingly, the strain Sjm18-20T is currently the only strain in this family having a validly published name. Figure 1 Phylogenetic tree highlighting the position of O. valericigenes strain Sjm18-20T relative to other representative type strains within the clostridial cluster IV. The tree was constructed by the neighbor-joining method  based on an alignment of 1,339 … Organism information Strain Sjm18-20T is a mesophilic, neutrophilic, strictly anaerobic bacterium with features as summarized in Table 1 . Unlike other clostridial bacteria, which are typically characterized as being low G+C content, Gram-positive, endospore-forming and anaerobic, Sjm18-20T is Gram-stain negative and non-sporulating.
Cells are straight to slightly curved rods with 0.4-0.6 �� 2.5-6.0 ��m in size. Cells are elongated after prolonged cultivation and often reach 30 ��m in length. Optimum growth is observed at 30��C and pH 6.0-6.5. The strain tolerates up to 4% NaCl, but growth is also observed in the absence of NaCl. Table 1 Classification and general features of Oscillibacter valericigenes Sjm18-20T Cells are motile with oscillatory movements. Electron microscopic observation demonstrated the presence of peritrichous flagella . In agreement with this observation, the genome encodes genes necessary for flagellar synthesis and chemotaxis, as is typical in many Gram-positive bacteria.
In contrast, while some clostridial bacteria, including the pathogenic species Clostridium perfringens, are known to utilize type IV pili for their gliding motility , neither genes encoding the constituents of type IV pili, nor the gld motility genes of Flavobacterium johnsoniae , were found in the Sjm18-20T genome, suggesting that flagella are solely responsible for the oscillatory movements. Strain Sjm18-20T grows poorly even in the medium supplemented with 0.5% each of yeast extract and polypeptone, with a generation time of 18.3 hours under optimum growth conditions . From the genome sequence, strain Sjm18-20T seems to be able to synthesize most amino acids, with the exception of branched-chain amino acids. The genome encodes, however, several ABC transporters possibly involved in the uptake of branched-chain amino acids (OBV_11160-11200, OBV_36860-6900 and OBV_40040-40050).
The strain grows fermentatively and produces acids from D-glucose, L-arabinose, D-ribose and D-xylose, with n-valeric acid being the major end product from glucose . Consistent with these observations, genes encoding catabolic enzymes and possible transporters for these GSK-3 sugars could be assigned on the genome. However, we could not identify a gene encoding the authentic form of enolase (EC 4.2.1.