Indexed on: 12 Dec '12Published on: 12 Dec '12Published in: Antonie van Leeuwenhoek
The taxonomic position of an orange coloured bacterium, strain K22-26(T) isolated from a soil sample was studied using a polyphasic approach. The organism had phenotypic and chemotaxonomic properties consistent with its allocation into the genus Exiguobacterium. Phylogenetic analysis of the 16S rRNA gene sequence showed that strain K22-26(T) belongs to the genus Exiguobacterium and was related to Exiguobacterium aurantiacum DSM 6208(T) (99.0 %) Exiguobacterium mexicanum DSM 16483(T) (98.6 %), Exiguobacterium aquaticum (98.6 %), Exiguobacterium aestuarii DSM 16306(T) (98.1 %), Exiguobacterium profundum DSM 17289(T) (98.1 %) and Exiguobacterium marinum DSM 16483(T) (97.9 %), whereas sequence similarity values with respect to other Exiguobacterium species with validly published names were between 92.5-94.0 %. The major polar lipids detected were phosphatidylglycerol, diphosphatidylglycerol and phosphatidylethanolamine. The major menaquinone was determined to be MK-7 (83 %) whereas MK-8 (11 %) and MK-6 (6 %) occur in smaller amounts. The peptidoglycan of the strain was found to contain L-lysine as the diagnostic diamino acid. The major fatty acids detected were iso C13:0 (11.2 %), anteiso C13:0 (15.4 %), iso C15:0 (13.2 %) and iso C17:0 (16.1 %). However, analysis of the DNA-DNA relatedness confirmed that strain K22-26(T) belongs to a novel species. The G + C content of the strain K22-26(T) was determined to be 50.1 mol %. The novel strain was distinguished from closely related type species of the genus Exiguobacterium using DNA-DNA relatedness and phenotypic data. Based on these differences, the strain K22-26(T) should be classified as a novel species of the genus Exiguobacterium, for which the name Exiguobacterium himgiriensis sp. nov. strain K22-26(T) (= MTCC 7628(T) = JCM 14260(T)) is proposed.