Bacteroides barnesiae sp. nov., Bacteroides salanitronis sp. nov. and Bacteroides gallinarum sp. nov., isolated from chicken caecum

Abstract

Eight bacterial strains isolated from the caecum of chicken, BL2T, BL66, EG3, EG6, M27, BL78T, C35T and C43, were characterized by determining their phenotypic characteristics, cellular fatty acid profiles, menaquinone profiles and phylogenetic positions based on 16S rRNA gene sequence analysis. 16S rRNA gene sequence analysis showed that these isolates belonged to the genus Bacteroides. One group of five strains (BL2T, BL66, EG3, EG6 and M27) was related most closely to Bacteroides coprocola JCM 12979T, with approximately 93 % 16S rRNA gene sequence similarity, and to Bacteroides plebeius JCM 12973T, with about 92 % similarity, and shared ⩾99.6 % similarity with each other. Strain BL78T exhibited 90.5 % similarity to B. plebeius JCM 12973T and 89.8 % similarity to B. coprocola JCM 12979T and differed from the above group of five strains at ⩾10 % sequence divergence. Strains C35T and C43 were related most closely to Bacteroides eggerthii JCM 12986T, with 95.1 % sequence similarity, to Bacteroides stercoris JCM 9496T, with 94.6 % similarity, and to Bacteroides uniformis JCM 5828T, with 94.4 % similarity, and shared 100 % similarity with each other. From results of phenotypic examination, cellular fatty acid composition analysis, menaquinone composition analysis and DNA G+C contents, the group of five strains as well as strain BL78T were shown to differ from the type strains of B. coprocola and B. plebeius. Strain BL78T differed from the others based on its menaquinone composition, which included MK-11 and MK-12. Strains C35T and C43 could also be differentiated from the type strains of B. eggerthii, B. stercoris and B. uniformis. The group of five strains, strain BL78T, B. coprocola JCM 12979T and B. plebeius JCM 12973T showed low levels of DNA–DNA relatedness (<35 %) with each other. High levels of DNA–DNA relatedness were obtained within the group of five strains (>75 %). Strains C35T and C43 exhibited a high level of DNA–DNA relatedness (>88 %) with each other, but low levels with B. eggerthii JCM 12986T (<40 %), B. stercoris JCM 9496T (<37 %) and B. uniformis JCM 5828T (<16 %). On the basis of these data, three novel Bacteroides species are proposed: Bacteroides barnesiae sp. nov. (type strain BL2T=JCM 13652T=DSM 18169T), Bacteroides salanitronis sp. nov. (type strain BL78T=JCM 13657T=DSM 18170T) and Bacteroides gallinarum sp. nov. (type strain C35T=JCM 13658T=DSM 18171T).