Characterization of Polaribacter formosus sp. nov. and Polaribacter salmoneus sp. nov. with Comparative Genomic Analysis of the Genus Polaribacter

Abstract

Two novel Gram-negative, rod-shaped, carotenoid-pigmented strains, Z022T and Z014T, were isolated from the viscera of abalone, Haliotis discus hannai, in Weihai, China and from coastal sediment samples collected at the Antarctica Great Wall station, respectively. Phylogenetic analysis of the 16S rRNA gene sequences and the 120 ubiquitous single-copy proteins showed both the strains belonged to the genus Polaribacter. Genomic analysis, including the average nucleotide identity (ANI), digital DNA-DNA hybridization (dDDH), amino acid identity (AAI), and percentage of conserved proteins (POCP) among Z022T, Z014T and the reference strains suggested that the strains were two novel species within the genus Polaribacter. Pan-genome analysis revealed that 1079 core genes were shared among the 33 Polaribacter genomes. Biogeographic distribution analysis indicated that the marine environments are the primary habitat of the Polaribacter strains. The strain Z014T could tolerate up to 0.3 mM CdCl2 under the tested conditions. The predominant cellular fatty acids of strain Z022T were iso-C15:0 and iso-C15:0 3-OH; the predominant cellular fatty acids of strain Z014T were iso-C15:0 3-OH, iso-C15:0 and C15:0 3-OH. The major polar lipids of strain Z022T were phosphatidylethanolamine (PE), aminolipid (AL) and three unidentified lipids (L1-3). The major polar lipids of strain Z014T were aminolipid (AL), aminoglycolipid (AGL) and four unidentified lipids (L1-4). According to the phenotypic, chemotaxonomic characterization, phylogenetic classification and genome analysis, Z022T and Z014T are identified as two novel species of the genus Polaribacter, for which the names Polaribacter formosus sp. nov. and Polaribacter salmoneus sp. nov. are proposed with the type strain Z022T (=MCCC 1H00505T = KCTC 92009T) and Z014T (=MCCC 1H00504T = KCTC 92010T), respectively.