Microcella alkaliphila sp nov., a novel member of the family Microbacteriaceae isolated from a non-saline alkaline groundwater, and emended description of the genus Microcella

A high-G+C-content Gram-positive bacterium, designated as strain AC4r(T), was isolated from a highly alkaline, non-saline groundwater environment (pH 11 center dot 4). This organism formed small rod-shaped cells, was aerobic, heterotrophic, catalase-positive and oxiclase-negative and had an optimum growth temperature of 35 degrees C and an optimum pH of 9 center dot 5. The strain possessed a B2 beta-type cell-wall peptidoglycan, with D-Orn as the diagnostic diamino acid. The major respiratory quinones were unsaturated menaquinones with 13 and 14 isoprene units. The predominant fatty acids were anteiso-15:0, iso-16:0, iso-14:0 and iso-15:0. The G + C content of the DNA was 67 center dot 1 mol%. In a 16S rRNA gene sequence analysis, strain AC4r(T) showed the highest level of similarity (99 center dot 2%) to the type strain of Microcella putealis; however, the DNA-DNA reassociation value between these two organisms was low (38 center dot 3%). On the basis of phylogenetic analysis, the DNA-DNA reassociation value and distinct phenotypic characteristics, strain AC4r(T) represents a novel species within the genus Microcella, for which the name Microcella alkaliphila sp. nov. is proposed. The type strain is AC4r(T) (=LMG 22690(T)=CIP 108473(T)).