sp. nov., a carbon monoxide-oxidizing acetogen isolated from old hay.

An acid/alcohol-producing, Gram-stain-positive, obligately anaerobic, rod-shaped, non-motile, non-spore forming acetogen, designated as strain P21, was isolated from old hay after enrichment with CO as the substrate. Spores not observed even after prolonged incubation (30 days). Phylogenetic analysis of the 16S rRNA gene sequence of strain P21 showed it was closely related to DSM 15243 (97.9%), DSM 757 (97.7 %) and DSM 12750 (97.7 %). The genome is 5.6 Mb and the G+C content is 29.4 mol%. Average nucleotide identity between strain P21, , and was 87.1, 86.4, 86.4 %, respectively. Strain P21 grew on CO:CO, H:CO, l-arabinose, ribose, xylose, fructose, galactose, glucose, lactose, mannose, cellobiose, sucrose, cellulose, starch, pyruvate, choline, glutamate, histidine, serine, threonine and casamino acids. End products of metabolism were acetate, butyrate, caproate, ethanol and hexanol. Dominant cellular fatty acids (>10 %) were C (41.5 %), C ω7/C ω6 (10.0 %), and a summed feature containing cyclo C/C (17.3 %). Based on the phenotypic, chemotaxonomic, phylogenetic and phylogenomic analyses, strain P21 represents a new species in the genus , for which the name sp. nov. is proposed. The type strain is P21 (=DSM 111390=NCIMB 15261).