Two novel strains (HT111-2T and HT170-2) of the genus Lactobacillus were isolated from Marmota himalayana faecal samples collected on the Qinghai-Tibet Plateau, PR China. The isolates were Gram-stain-positive, rod-shaped, non-spore-forming bacteria with irregular circular colonies. Phylogenetic analysis and comparison of the 16S rRNA gene sequences demonstrated that the two strains form a subcluster and are closest to Lactobacillus hamsteri JCM 6256T (97.3 %) and Lactobacillus amylolyticus DSM 11664T (97.2 %). Phylogenetic analysis of two housekeeping genes (rpoA and pheS) found that strains HT111-2T and HT170-2 had the same closest relatives as the 16S rRNA gene sequence analysis did. The G+C content of strains HT111-2T and HT170-2 were 38.8 mol%. The values of in silico DNA-DNA hybridization with known Lactobacillus species were lower than the threshold (70%). Average nucleotide identity values of strain HT111-2T with L. hamsteri JCM 6256T and L. amylolyticus DSM 11664T were 77.84 % and 76.85 %, respectively. The major fatty acids of strains HT111-2T and HT170-2 were C16 : 0, C18 : 1ω9c and C18 : 0. Results of phenotypic, chemotaxonomic and phylogenetic analyses suggest strains HT111-2T and HT170-2 represent a novel species of the genus Lactobacillus, for which the name Lactobacillus xujianguonis sp. nov. is proposed with HT111-2T (=CGMCC 1.13855T=KCTC 15803T) as the type strain.
Keywords: Lactobacillus xujianguonis sp. nov; Qinghai-Tibet Plateau; novel species.