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-16(T), TF-19 and TF-80(T), 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 degrees 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-C(17 : 0), anteiso-C(13 : 0), iso-C(13 : 0) and iso-C(15 : 0). The DNA G+C contents of strains TF-16(T), TF-19 and TF-80(T) 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-16(T) and TF-19 and strain TF-80(T) are members of two species that are separate from E. aurantiacum. On the basis of phenotypic, phylogenetic and genetic data, strains TF-16(T) and TF-19 and strain TF-80(T) represent two novel species in the genus Exiguobacterium; the names Exiguobacterium aestuarii sp. nov. (type strain TF-16(T)=KCTC 19035(T)=DSM 16306(T); reference strain TF-19) and Exiguobacterium marinum sp. nov. (type strain TF-80(T)=KCTC 19036(T)=DSM 16307(T)) are proposed.