Bacteroides koreensis sp. nov. and Bacteroides kribbi sp. nov., two new members of the genus Bacteroides

Abstract

Three bacterial isolates from human faeces, YS-aM39T, R2F3-3-3T and R2F3-5-1, were characterized as Gram-negative, strictly anaerobic, non-spore-forming, non-motile, and rod-shaped. Isolate YS-aM39T formed a distinct line of descent, showing greatest 16S rRNA gene sequence relatedness with R2F3-3-3T (97.5%), R2F3-5-1 (97.5%), Bacteroides ovatus (98.8%) and Bacteroides xylanisolvens (97.2%). Isolates R2F3-3-3T and R2F3-5-1 also formed a distinct line of descent, sharing greatest 16S rRNA gene sequence relatedness with B. ovatus (98.2%) and B. xylanisolvens (97.2%). The DNA G+C content of YS-aM39T was 44.8 mol%, that of R2F3-3-3T was 42.4 mol% and that of R2F3-5-1 was 42.6 mol%. The respiratory quinone of all three isolates was menaquinone MK-10. Polar lipid analysis identified phosphatidylethanolamine as the major lipid. The predominant fatty acids in all three isolates were anteiso-C15: 0, iso-C15: 0, C16: 0 3-OH and iso-C17: 0 3-OH. The major end products of glucose fermentation were acetic acid, lactic acid and formic acid. DNA？DNA hybridization data indicated that two isolates, YS-aM39T and R2F3-3-3T, represent a species distinct from B. ovatus and B. xylanisolvens. Finally, in this study, the two isolates represented two new species in the genus Bacteroides, for which we propose the names Bacteroides koreensis sp. nov. (type strain, YS-aM39T=KCTC 15520T=JCM 31393T) and Bacteroides kribbi sp. nov. (type strain, R2F3-3-3T=KCTC 15460T=JCM 31391T).