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

Abstract

A high-G+C-content Gram-positive bacterium, designated as strain AC4rT, was isolated from a highly alkaline, non-saline groundwater environment (pH 11.4). This organism formed small rod-shaped cells, was aerobic, heterotrophic, catalase-positive and oxidase-negative and had an optimum growth temperature of 35 °C and an optimum pH of 9.5. The strain possessed a B2β-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 67.1 mol%. In a 16S rRNA gene sequence analysis, strain AC4rT showed the highest level of similarity (99.2 %) to the type strain of Microcella putealis; however, the DNA–DNA reassociation value between these two organisms was low (38.3 %). On the basis of phylogenetic analysis, the DNA–DNA reassociation value and distinct phenotypic characteristics, strain AC4rT represents a novel species within the genus Microcella, for which the name Microcella alkaliphila sp. nov. is proposed. The type strain is AC4rT (=LMG 22690T=CIP 108473T).