Microbacterium kyungheense sp. nov. and Microbacterium jejuense sp. nov., isolated from salty soil.

Abstract

Two novel strains, THG-C26(T) and THG-C31(T), were characterized using a polyphasic approach to determine their taxonomic positions. These two isolates were aerobic, Gram-stain-positive, non-motile, non-spore-forming and rod-shaped. 16S rRNA gene sequences and phenotypic features including chemotaxonomic characteristics indicated that the two isolates clearly represented members of the genus Microbacterium. The quinone systems of strains THG-C26(T) and THG-C31(T) contained MK-12/MK-13 as major menaquinones. The diamino acid in cell-wall hydrolysates of the two strains was ornithine. The major fatty acids were iso-C16 : 0, anteiso-C15 : 0 and anteiso-C17 : 0. The polyamine pattern had spermidine as the predominant component. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol and unidentified glycolipids. Phenotypic characteristics supported the affiliation of strains THG-C26(T) and THG-C31(T) to the genus Microbacterium. Chemotaxonomic data and DNA-DNA relatedness values allowed differentiation of these strains from other species of the genus Microbacterium with validly published names. Strains THG-C26(T) and THG-C31(T) showed highest 16S rRNA gene sequence similarities with Microbacterium resistens DMMZ 1710(T) (98.5%) and Microbacterium trichothecenolyticum IFO 15077(T) (98.8%), respectively, and the 16S rRNA gene sequence similarity between them was 99.0%. DNA-DNA hybridization values between the novel isolates and strains of other species of the genus Microbacterium with validly published names were 4-25%. Therefore, strains THG-C26(T) and THG-C31(T) are considered to represent two novel species of the genus Microbacterium, for which the names Microbacterium kyungheense sp. nov. [type strain THG-C26(T) ( = KACC 17124(T) = JCM 18735(T))] and Microbacterium jejuense sp. nov. [type strain THG-C31(T) ( = KACC 17123(T) = JCM 18734(T))] are proposed.