Aestuariirhabdus litorea gen. nov., sp. nov., isolated from a sea tidal flat and proposal of Aestuariirhabdaceae fam. nov.

Abstract

A Gram-negative, moderately halophilic and facultatively aerobic bacterium, designated strain GTF13T, was isolated from a sea tidal flat. Cells were curved rods and motile by a single polar flagellum showing catalase and oxidase activities. Growth was observed at 20–37 °C, pH 5.0–8.5 and 1.0–6.0% (w/v) NaCl. Strain GTF13T contained C16:0, summed feature 3 (comprising C16:1 ω6c/C16:1 ω7c), summed feature 8 (comprising C18:1 ω6c/C18:1 ω7c) and C12:0 3-OH as major fatty acids and ubiquinone-9 and ubiquinone-8 as major quinones. Phosphatidylethanolamine and two unidentified phospholipids were detected as major polar lipids. The G+C content of the genomic DNA was 59.8 mol%. Strain GTF13T was most closely related to Simiduia agarivorans SA1T, Endozoicomonas montiporae CL-33T and Pseudomonas segetis FR1439T, belonging to different families or orders of the class Gammaproteobacteria, with less than 92.0% 16S rRNA gene sequence similarities. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain GTF13T formed a phylogenetic lineage with the family Litoricolaceae, but the genomebased phylogenomic tree showed that strain GTF13T formed a distinct phylogenetic lineage within the order Oceanospirillales. The very low 16S rRNA gene sequence similarities and distinct phylogenetic relationships, together with distinct phenotypic and chemotaxonomic properties, served to differentiate strain GTF13T from phylogenetically closely related families. Here, strain GTF13T is proposed as a novel genus and species, for which the name Aestuariirhabdus litorea gen. nov., sp. nov. is proposed, within a new family Aestuariirhabdaceae fam. nov. of the order Oceanospirillales. The type strain is GTF13T (=KACC 19788T=JCM 32043T). © 2020 The Authors.