Tenacibaculum piscium sp. nov., isolated from skin ulcers of sea-farmed fish, and description of Tenacibaculum finnmarkense sp. nov. with subdivision into genomovars finnmarkense and ulcerans

Abstract

Results of previous multilocus sequence and whole-genome-based analyses have suggested that a homogeneous group of isolates belonging to the genus <i>Tenacibaculum</i>, represented by strain TNO020^T and associated with skin ulcer development in sea-farmed fish, represents an as-yet-undescribed species. Comparative whole-genome analysis performed in the present study clustered five isolates, including TNO020^T, in a distinct lineage within the genus <i>Tenacibaculum</i>. Phenotypic differences, high intra-cluster average nucleotide identity (ANI) values and low ANI values with other <i>Tenacibaculum</i> species support the proposal of a novel species, for which we propose the name <i>Tenacibaculum piscium</i> sp. nov. with strain TNO020^T (=CCUG 73833^T=NCIMB 15240^T) as the type strain. Further, large-scale genome analyses confirmed the existence of two different phylogenetic lineages within '<i>T. finnmarkense</i>', a species effectively but not validly published previously. ANI values just above the species delineation threshold of 95-96 % confirmed that both lineages belong to the same species. This result was also supported by DNA-DNA hybridization values. Phenotypically, the two conspecific lineages are distinguishable by differences in growth temperature range and ability to degrade l-proline. For the group of isolates already commonly known as '<i>T. finnmarkense</i>', we propose the name <i>Tenacibaculum finnmarkense</i> sp. nov., with strain TNO006^T (=CCUG 73831^T=NCIMB 15238^T) as the type strain. We further propose the subdivision of <i>T. finnmarkense</i> sp. nov. into two genomovars, <i>T. finnmarkense</i> genomovar <i>finnmarkense</i> with strain TNO006^T (=CCUG 73831^T=NCIMB 15238^T) as the type strain and <i>T. finnmarkense</i> genomovar <i>ulcerans</i> with strain TNO010^T (=CCUG 73832^T=NCIMB 15239^T) as the type strain.