Abstract
Three previously uncharacterized bacterial species, designated strains BD586(T), BD613(T) and BD626(T), isolated from human clinical specimens, were identified at Mayo Clinic, Rochester, Minnesota, USA. Initial identification efforts using matrix-assisted laser desorption ionization-time-of-flight MS and partial 16S rRNA gene sequencing proved inconclusive. Comprehensive analysis involving phenotypic characterization, biochemical assays and whole-genome sequencing was undertaken. The isolates were Gram-negative, motile, facultatively anaerobic rods, occurring singly, in pairs and in short chains; BD613(T) additionally formed small aggregates. The isolates tested positive for catalase and negative for oxidase. Their colonies appeared smooth, white, opaque and non-haemolytic. Growth was observed at 35 °C under aerobic, anaerobic and CO₂-enriched conditions, as well as in media with NaCl concentrations up to 10% and at pH 7-9. Phylogenetic relationships were inferred from core gene alignments, average nucleotide identity and digital DNA-DNA hybridization comparisons. Results confirmed the placement of BD586(T), BD613(T) and BD626(T) within the recently established Dryocola genus, while also indicating their novelty as distinct species. The major cellular fatty acids were C(16:0) and C(17:0) cyclo. Based on these findings, a formal description of three new species, Dryocola mayonis sp. nov. (type strain BD586(T)=TSD 474(T), =NCTC 15089(T), =DSM 119465(T)), Dryocola sharpae sp. nov. (type strain BD613(T)=TSD 475(T), =NCTC 15090(T), =DSM 119466(T)) and Dryocola baronae sp. nov. (type strain BD626(T)=TSD 476(T), =NCTC 15091(T), =DSM 119479(T)), is proposed, and the genus description of Dryocola is emended to refine its genomic, morphological and chemotaxonomic boundaries.