Parabacteroides leei sp. nov., isolated from human blood

An obligate anaerobic, Gram-negative, rod-shaped and non-spore-forming bacterium, designated as strain GYB001^T, was isolated from the blood of a patient with a sigmoid colon perforation. Taxonomic characterization of the novel isolate was performed using a polyphasic approach. A phylogenetic analysis based on 16S rRNA gene and whole genome sequences revealed that GYB001^T represented a member of the genus Parabacteroides, in the family Tannerellaceae. The closest species, based on 16S rRNA sequence, was Parabacteroides gordonii DSM 23371^T with 97.4 % similarity. Average nucleotide identity and digital DNA-DNA hybridization values between strain GYB001^T and P. gordonii DSM 23371^T were 86.7 and 28.7% and between GYB001^T and Parabacteroides faecis JCM 18682^T were 86.6 and 27.7 %, respectively. The genome was 6.57 Mbp long with 43.3 mol% G+C content. Colonies on Brucella blood agar (BBA) were circular, convex, smooth, grey and small in size. Growth was observed on trypticase soy agar (TSA), TSA +5 % sheep blood and Euglena gracilis agar. Growth occurred at 18-42 °C on BBA in the presence of 0-3 % NaCl (w/v) and at pH 6.0-8.5. The major polar lipids were phosphatidylethanolamine and phospholipids. The major fatty acids in strain GYB001^T were anteiso-C_15 : 0 and iso-C_17 : 0 3-OH, and the predominant respiratory quinones were menaquinone-10 (MK-10) and MK-9. The cell wall contained meso-diaminopimelic acid. Considering these phenotypic features and comparative genome analyses, we propose strain GYB001^T as the type strain of Parabacteroides leei sp. nov. (=KCTC 25738^T=KBN12P06525^T=LMG 32797^T).