Simiduia curdlanivorans sp. nov., a curdlan-degrading bacterium isolated from the junction between the ocean and a freshwater spring, and emended description of the genus Simiduia

Abstract

A Gram-stain-negative, aerobic, non-spore-forming, non-flagellated and rod-shaped bacterial strain, designated DMCK3-4T, was isolated from the zone where the ocean and a freshwater spring meet at Jeju island, South Korea. Strain DMCK3-4T grew optimally at 30 °C, at pH 7.0–8.0 and in the presence of 2.0 % (w/v) NaCl. Phylogenetic trees based on 16S rRNA gene sequences revealed that strain DMCK3-4T clustered with the strains of three members of the genus Simiduia , with which it exhibited 97.0–99.0 % sequence similarity. Sequence similarities to the type strains of the other species with validly published names were less than 92.2 %. Strain DMCK3-4T contained Q-8 as the predominant ubiquinone and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C17 : 1ω8c, C16 : 0, C17 : 0 and C18 : 1ω7c as the major fatty acids. The major polar lipids of strain DMCK3-4T were phosphatidylethanolamine, phosphatidylglycerol, two unidentified glycolipids, one unidentified lipid and one unidentified aminolipid. The DNA G+C content of strain DMCK3-4T was 51.8 mol% and its mean DNA–DNA relatedness values with Simiduia agarivorans KCTC 23176T, Simiduia areninigrae KCTC 23293T and Simiduia litorea NRIC 0917T were 23–34 %, respectively. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strain DMCK3-4T is distinct from other species of the genus Simiduia . On the basis of the data presented, strain DMCK3-4T is considered to represent a novel species of the genus Simiduia , for which the name Simiduia curdlanivorans sp. nov. is proposed. The type strain is DMCK3-4T ( = KCTC 42075T = CECT 8570T). An emended description of the genus Simiduia is also proposed.