Corynebacterium mayonis sp. nov. isolated from a human blood culture.

Abstract

A novel Corynebacterium species, strain BD556^T, isolated from blood, was identified at Mayo Clinic, Rochester, MN, USA. After failing definitive identification using MALDI-ToF MS and partial 16S rRNA gene sequencing, BD556^T was characterized using a polyphasic approach, including phenotypic, biochemical and whole-genome sequencing methods. BD556^T was a Gram-positive rod with clubbed ends, facultatively anaerobic, catalase-positive, oxidase-negative and non-motile. Colonies were white, opaque and non-haemolytic with halo-like edges. BD556^T grew at 35 °C in room air, with CO₂ and under anaerobic conditions. BD556^T grew well in 0 and 6% NaCl and weakly in 10% NaCl. The genome size was 2 349 779 bp with a G+C content of 60.39%. Phylogenetic analysis using 16S rRNA gene sequence analysis, average nucleotide identity and digital DNA-DNA hybridization between the genome of BD556^T and the closest type strains from the Type Strain Genome Server database yielded separation values well beyond those required for species delineation. Chemotaxonomic analyses of BD556^T revealed ribose, arabinose and galactose as whole-cell sugars and an A1γ meso-diaminopimelic acid-direct peptidoglycan type. The major cellular fatty acids were C_15 : 0 (21.0%), C_16 : 0 (14.8%), C_17 : 1 ω9c (26.2%), C_17 : 0 (13.3%) and C_18 : 1 ω9c (18.3%). Polar lipids included diphosphatidylglycerol, phosphatidylglycerol and unidentified glycolipids and phospholipids. BD556^T also contained mycolic acids (32-36 carbons) typical of corynebacteria. The respiratory quinones were dominated by MK-8(H₂) (71.2%) and MK-9(H₂) (25.9%), with smaller amounts of MK-7(H₂) and MK-10(H₂). The results presented support the tenet that BD556^T (=TSD 427^T=NCTC 15078^T) is a novel species for which the name Corynebacterium mayonis sp. nov. is proposed.