Emended description of Salinivibrio proteolyticus, including salinivibrio costicola subsp. Vallismortis and five new isolates

Abstract

We carried out a comparative taxonomic study of Salinivibrio proteolyticus and Salinivibrio costicola subsp. vallismortis, as well as of five halophilic strains (IB574, IB872, PR5, PR919 and PR932), isolated from salterns in Spain and Puerto Rico that were closely related to these bacteria. Multilocus sequence analysis of concatenated gyrB, recA, rpoA and rpoD housekeeping genes showed that they constituted a single cluster separate from the other species and subspecies of Salinivibrio. Experimental and in silico DNA–DNA hybridization studies indicated that they are members of the same species, with relatedness of 100–74% and 97.8–70.0 %, respectively. The average nucleotide identity (ANI) determined for these strains was 99.7–95.6% for ANIb and 99.7–95.7% for OrthoANI. However, the ANI values for S. costicola subsp. vallismortis DSM 8285T with respect to S. costicola subsp. costicola DSM 11403T and S. costicola subsp. alcaliphilus DSM 16359T were 78.7 and 78.9% (ANIb) and 79.4 and 79.4% (OrthoANI), respectively. The phylogenomic tree based on 1072 concatenated orthologous single-copy core genes confirmed that S. proteolyticus, S. costicola subsp. vallismortis and the five new isolates constitute a coherent single phylogroup, separated from the other species and subspecies of Salinivibrio. All these data indicate that S. costicola subsp. vallismortis is a heterotypic synonym of S. proteolyticus and we propose an emended description of this species.