Bacteroides luhongzhouii sp. nov. and Bacteroides zhangwenhongii sp. nov., isolated from human faeces

Abstract

Four unknown strains, characterized as Gram-stain-negative, strictly anaerobic, non-motile and rod-shaped, were isolated from fresh faeces of healthy humans in PR China. Pairwise sequence comparisons of the 16S rRNA genes showed that these isolates were separated into two clusters. Cluster I (strains HF-5141^T and HF-106) was most closely related to Bacteroides xylanisolvens XB1A^T (98.0-98.3 % similarity) and Bacteroides ovatus ATCC 8483^T (97.3-97.5 %), whereas cluster II (strains HF-5287^T and HF-5300) exhibited a similarity range of 96.8-97.0 % to Bacteroides finegoldii JCM 13345^T, 96.7-96.9 % to Bacteroides faecis MAJ27^T and 96.4-96.5 % to Bacteroides xylanisolvens XB1A^T. The DNA G+C contents of type strains HF-5141^T and HF-5287^T were 41.5 and 42.6 mol%, respectively. These strains had anteiso-C_{15 : 0} as the major cellular fatty acid, MK-9 and MK-11 as the predominant respiratory quinones, and phosphatidylethanolamine, aminophospholipids and phospholipids as major polar lipids, which is typical for members of the genus Bacteroides. However, the average nucleotide identity and digital DNA-DNA hybridization values, accompanied by different phenotypic and biochemical characteristics, distinguished them from their corresponding closest relatives as well as from other recognized members of the genus Bacteroides. Therefore, strains HF-5141^T and HF-5287^T represent two novel species in the genus Bacteroides, for which the names Bacteroides luhongzhouii sp. nov. and Bacteroides zhangwenhongii sp. nov. are proposed, with HF-5141^T (=CGMCC 1.16787^T=GDMCC 1.1591^T=JCM 33480^T) and HF-5287^T (=CGMCC 1.16724^T=GDMCC 1.1590^T=JCM 33481^T) as type strains.

Keywords: Bacteroides luhongzhouii; Bacteroides zhangwenhongii; gut microbiota; taxonomy.