Genome-based classification of the family Haloferacaceae and description of five novel species of Halobaculum.

Abstract

The taxonomic status of some species of Halobellus, Haloferax, Halogranum, and Haloplanus within the family Haloferacaceae was elucidated by phylogenetic, phylogenomic, and comparative genomic analyses. The relative species of each genus should constitute a single species based on the overall genome-related indexes proposed for species demarcation. The cutoff values of AAI (72.1%), ANI (82.2%), and rpoB' gene similarity (90.7%) were proposed to differentiate genera within the family Haloferacaceae. According to these standards, a novel genus related to the genus Halobaculum was proposed to accommodate Halobaculum halophilum Gai3-2 ^T and Halobaculum salinum NJ-3-1 ^T. Five halophilic archaeal strains, DT31^T, DT55^T, DT92^T, SYNS20^T, and YSMS11^T, isolated from a tidal flat and a marine solar saltern in China, were subjected to polyphasic classification. The phenotypic, phylogenetic, phylogenomic, and comparative genomic analyses revealed that strains DT31^T (= CGMCC 1.18923 ^T = JCM 35417 ^T), DT55^T (= CGMCC 1.19048 ^T = JCM 36147 ^T), DT92^T (= CGMCC 1.19057 ^T = JCM 36148 ^T), SYNS20^T (= CGMCC 1.62628 ^T = JCM 36154 ^T), and YSMS11^T (= CGMCC 1.18927 ^T = JCM 34912 ^T) represent five novel species of the genus Halobaculum, for which the names, Halobaculum lipolyticum sp. nov., Halobaculum marinum sp. nov., Halobaculum litoreum sp. nov., Halobaculum halobium sp. nov., and Halobaculum limi sp. nov., are proposed.