Comparative genomic analysis and characterization of Staphylococcus sp. AOAB, isolated from a notoriously invasive Mnemiopsis leidyi gut revealed multiple antibiotic resistance determinants

Here, we describe the isolation and characterization of a coagulase-negative, vancomycin and oxacillin-susceptible novel bacterium of the genus Staphylococcus. Staphylococcus sp. strain AOAB was isolated from the stomodeum (gut) of the Mnemiopsis leidyi from Mobile Bay, Alabama USA. A polyphasic taxonomic approach comprised of phenotypic, chemotaxonomic and genotypic characteristics was used for analysis. The dominant respiratory quinone detected was MK-7 (100%). Major cellular fatty acids were anteiso-C15:0 (40.52%), anteiso-C17:0 (13.04 %), C-18:0 (11.53%) and C-20:0 (10.45%). The polar lipid profile consisted of glycolipid, phospholipid, phosphatidylglycerol and diphosphatidylglycerol. Although strain AOAB had a 16SrRNA gene sequence similarity of 99% with S. warneri SG1, S. pasteuri, S. devriesei KS-SP_60, S. lugdunensis HKU09-01, S. epidermidis RP62A, S. haemolyticus JCSC1435 and S. hominis DM 122, it was be distinguished from those species based on Multi-Locus Sequence Analysis (MLSA) using 6 marker genes (16S rRNA, hsp60, rpoB, dnaJ, sodA and tuf). MLSA revealed strain AOAB to be closely related to S. warneri SG1 and S. pasteuri SP1 but distinct from two hitherto known species. These results were confirmed by Average Nucleotide Identity (closest ANI of 84.93% and 84.58% identity against S. warneri SG1 and S. pasteuri SP1 respectively). In-silico DNA-DNA hybridization was <70% (33.1 % and 32.8% against S. warneri SG1 and S. pasteuri SP1 respectively), which further confirmed that the strain was a potential novel Staphylococcus species.