Isolation of bacteria from mouse caecal samples and description of Bacteroides sartorii sp. nov

Caecal samples from wild-type and TNF^deltaARE mice were cultured on selective media containing bile salts, amino acids or casein macro-peptides. Twenty-two strains were isolated and identified by 16S rRNA gene sequencing. Twenty-one strains showed ≥98% similarity to known bacteria (Blautia spp., Clostridium innocuum, Enterococcus spp., Escherichia coli, Lactobacillus murinus, Parabacte-roides goldsteinii and Shigella dysenteriae). One additional isolate, strain A-C2-0, was a new bacterium. The closest relatives were Bacteroides massiliensis, Bacteroides dorei and Bacteroides vulgatus (<94% similarity). Strain A-C2-0 is a Gram-negative rod that does not form spores and has a G + C content of DNA of 41.5%. Its major cellular fatty acid is C _{15:0 ANTEISO}, and its major respiratory quinone is MK-9. Cells are aerotolerant but grow only under strict anoxic conditions. They are resistant to cefotaxime and tobramycin. When compared with related Bacteroides spp., the new bacterium was positive for a-arabinosidase, negative for glutamyl glutamic acid arylamidase and did not metabolise galactose, glucose, fructose, mannose, raffinose and sucrose. Strain A-C2-0 therefore merits recognition as a member of a novel species within the genus Bacteroides, for which the name Bacteroides sartorii is proposed. The type strain is A-C2-0^T (= DSM 21941 ^T = CCUG 57211^T).