Exiguobacterium aestuarii sp. nov. and Exiguobacterium marinum sp. nov., isolated from a tidal flat of the Yellow Sea in Korea

Abstract

Three Gram-variable, rod-shaped bacterial strains, TF-16T, TF-19 and TF-80T, were isolated from a tidal flat of Daepo Beach (Yellow Sea) near Mokpo City, Korea, and their taxonomic positions were investigated by a polyphasic approach. These isolates grew optimally in the presence of 2% NaCl and at 30 °C. Their peptidoglycan types were based on L-Lys-Gly. The predominant menaquinone detected in the three strains was MK-7. The three strains contained large amounts of the branched fatty acids iso-C17:0, anteiso-C13:0, iso-C13:0 and iso-C15:0. The DNA G+C contents of strains TF-16T, TF-19 and TF-80T were 48.6, 48.4 and 48.0 mol%, respectively. The three strains formed a coherent cluster with Exiguobacterium species in a phylogenetic tree based on 16S rRNA gene sequences. They showed closest phylogenetic affiliation to Exiguobacterium aurantiacum, with 16S rRNA gene sequence similarity values of 98.1-98.3%. The three strains exhibited 16S rRNA gene sequence similarity values of 94.0-94.6% to the type strains of other Exiguobacterium species. Levels of DNA-DNA relatedness indicated that strains TF-16T and TF-19 and strain TF-80T are members of two species that are separate from E. aurantiacum. On the basis of phenotypic, phylogenetic and genetic data, strains TF-16T and TF-19 and strain TF-80T represent two novel species in the genus Exiguobacterium; the names Exiguobacterium aestuarii sp. nov. (type strain TF-16T=KCTC 19035T=DSM 16306T; reference strain TF-19) and Exiguobacterium marinum sp. nov. (type strain TF-80T=KCTC 19036T-DSM 16307T) are, proposed.