Parabacteroides leei sp. nov., isolated from human blood

Abstract

An obligate anaerobic, Gram-negative, rod-shaped and non-spore-forming bacterium, designated as strain GYB001T, 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 GYB001T represented a member of the genus Parabacteroides, in the family Tannerellaceae. The closest species, based on 16S rRNA sequence, was Parabacteroides gordonii DSM 23371T with 97.4% similarity. Average nucleotide identity and digital DNA–DNA hybridization values between strain GYB001T and P. gordonii DSM 23371T were 86.7 and 28.7% and between GYB001T and Parabacteroides faecis JCM 18682T 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 GYB001T were anteiso-C15:0 and iso-C17:0 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 GYB001T as the type strain of Parabacteroides leei sp. nov. (=KCTC 25738T=KBN12P06525T=LMG 32797T).