Confluentimicrobium lipolyticum gen. nov., sp. nov., a novel lipolytic alphaproteobacterium isolated from the junction between the ocean and a freshwater spring, and emended description of Actibacterium mucosum Lucena et al. 2012.

Abstract

A Gram-negative, aerobic, non-flagellated and coccoid, ovoid or rod-shaped bacterial strain, designated SSK1-4(T), was isolated from the junction between the ocean and a freshwater spring at Jeju island, South Korea. Strain SSK1-4(T) was found to grow optimally at 30°C, at pH 7.0-8.0 and in the presence of 2.0% (w/v) NaCl. In the neighbour-joining, maximum-likelihood and maximum-parsimony phylogenetic trees based on 16S rRNA gene sequences, strain SSK1-4(T) was found to form an evolutionary lineage independent of those of other genera within the family Rhodobacteraceae. Strain SSK1-4(T) exhibited the highest 16S rRNA gene sequence similarity values to the type strains of Ruegeria lacuscaerulensis (94.99%), Ruegeria atlantica (94.98%) and Rhodovulum marinum (94.97%). Sequence similarities to the type strains of other recognized species were less than 94.87%. Strain SSK1-4(T) was found to contain Q-10 as the predominant ubiquinone and C18:1 ω7c and cyclo-C19:0 ω8c as the major fatty acids. The polar profile of strain SSK1-4(T) was found to contain phosphatidylglycerol, sulfoquinovosyldiacylglycerol, an unidentified lipid and an unidentified aminolipid as major components, which distinguish it from those of the phylogenetically related taxa. The DNA G+C content of strain SSK1-4(T) was determined to be 58.4mol%. On the basis of the phylogenetic data and the chemotaxonomic and other phenotypic properties, strain SSK1-4(T) is considered to represent a new genus and species within the class Alphaproteobacteria, for which the name Confluentimicrobium lipolyticum gen. nov., sp. nov. is proposed. The type strain of C. lipolyticum is SSK1-4(T) (=KCTC 42136(T)=CECT 8621(T)). In addition, an emended description of Actibacterium mucosum Lucena et al. 2012 is also proposed.