Marinobacter confluentis sp. nov., a lipolytic bacterium isolated from a junction between the ocean and a freshwater lake.

Abstract

A Gram-stain-negative, motile, aerobic and rod-shaped bacterium, designated HJM-18T, was isolated from the place where the ocean and a freshwater lake meet at Hwajinpo, South Korea, and subjected to a taxonomic study using a polyphasic approach. Strain HJM-18T grew optimally at 30 °C, at pH 7.0-8.0 and in the presence of 1.0-3.0 % (w/v) NaCl. Phylogenetic trees based on 16S rRNA gene sequences showed that strain HJM-18T belonged to the genus Marinobacter. Strain HJM-18T exhibited 16S rRNA gene sequence similarity values of 97.05-98.22 % to the type strains of Marinobacter algicola, Marinobacter flavimaris, Marinobacter adhaerens, Marinobacter salarius, Marinobacter salsuginis, Marinobacter guineae and Marinobacter gudaonensis and of 93.21-96.98 % to the type strains of the other species of the genus Marinobacter. Strain HJM-18T contained Q-9 as the predominant ubiquinone and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and C18 : 1ω9c as the major fatty acids. The major polar lipids detected in strain HJM-18T were phosphatidylethanolamine, phosphatidylglycerol and one unidentified aminophospholipid. The DNA G+C content was 58 mol% and the mean DNA-DNA relatedness values with the type strains of the seven phylogenetically related species of the genus Marinobacter were 10-27 %. Differential phenotypic properties, together with phylogenetic and genetic distinctiveness, revealed that strain HJM-18T is separated from recognized species of the genus Marinobacter. On the basis of the data presented, strain HJM-18T represents a novel species of the genus Marinobacter, for which the name Marinobacter confluentis sp. nov. is proposed. The type strain is HJM-18T ( = KCTC 42705T = NBRC 111223T).