Defluviimonas aquaemixtae sp. nov., isolated from the junction between a freshwater spring and the ocean

Abstract

A Gram-stain-negative, coccoid- or short-rod-shaped and non-gliding bacterial strain, designated CDM-7T, was isolated from the zone where the ocean meets a freshwater spring at Jeju island, South Korea, and was subjected to a polyphasic taxonomic study. Strain CDM-7T grew optimally at pH 7.0–8.0, at 30 °C and in the presence of 2–3 % (w/v) NaCl. Neighbour-joining, maximum-likelihood and maximum-parsimony phylogenetic trees based on 16S rRNA gene sequences showed that strain CDM-7T falls within the clade comprising species of the genus Defluviimonas, clustering with the type strain of Defluviimonas aestuarii , with which it exhibited the highest 16S rRNA gene sequence similarity value (98.4 %). The 16S rRNA gene sequence similarity values between strain CDM-7T and the type strains of Defluviimonas denitrificans and Defluviimonas indica were 97.1 and 96.2 %, respectively. The genomic DNA G+C content was 66.8 mol% and the mean DNA–DNA relatedness values between strain CDM-7T and the type strains of D. aestuarii and D. denitrificans were 15.6±2.5 and 6.7±3.2 %, respectively. Strain CDM-7T contained Q-10 as the predominant ubiquinone and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) as the major fatty acid. The major polar lipids were phosphatidylcholine, phosphatidylglycerol, an unidentified aminolipid, an unidentified phospholipid and an unidentified lipid. Differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, demonstrated that strain CDM-7T is distinguishable from other species of the genus Defluviimonas . On the basis of the data presented, strain CDM-7T is considered to represent a novel species of the genus Defluviimonas , for which the name Defluviimonas aquaemixtae sp. nov. is proposed. The type strain is CDM-7T ( = KCTC 42108T = CECT 8626T).