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

A Gram-reaction-negative, aerobic, non-spore-forming, non-motile and rod-shaped or ovoid bacterial strain, designated SSK6-1(T), was isolated from the zone where the ocean and a freshwater spring meet at Jeju island, South Korea. Strain SSK6-1(T) grew optimally at 30 °C, at pH 7.0-7.5 and in the presence of 2.0 % (w/v) NaCl. Phylogenetic trees based on 16S rRNA gene sequences revealed that strain SSK6-1(T) clustered with Phaeobacter daeponensis TF-218(T) and Phaeobacter caeruleus LMG 24369(T), exhibiting sequence similarities of 98.6 and 98.3 %, respectively. The novel strain exhibited sequence similarities of 94.6-97.8 % to the type strains of other recognized species of the genera Phaeobacter and Leisingera. Strain SSK6-1(T) contained Q-10 as the predominant ubiquinone and C18 : 1ω7c and 11-methyl C18 : 1ω7c as the major fatty acids. The major polar lipids of strain SSK6-1(T) were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, one unidentified aminolipid and one unidentified lipid. The DNA G+C content of strain SSK6-1(T) was 64.6 mol% and its DNA-DNA relatedness values with P. daeponensis TF-218(T) and P. caeruleus were 21 and 25 %, respectively. The differential phenotypic properties, together with phylogenetic and genetic distinctiveness, revealed that strain SSK6-1(T) is separate from recognized Phaeobacter species. On the basis of the data presented, strain SSK6-1(T) is considered to represent a novel species of the genus Phaeobacter, for which the name Phaeobacter aquaemixtae sp. nov. is proposed. The type strain is SSK6-1(T) ( = KCTC 32538(T) = CECT 8399(T)).