Mycolicibacter acidiphilus sp. nov., an extremely acid-tolerant member of the genus Mycolicibacter

Abstract

A nonmotile, facultatively anaerobic and rod-shaped bacterial strain, designated M1T was isolated from a bioreactor being operated at pH ~2 at Brisbane, Australia. Colonies appeared to be convex and white. Phylogenetic analysis of its genome revealed an affiliation with the genus Mycolicibacter and its closest species based on 16S rRNA gene analysis were Mycolicibacter algericus DSM 45454T (98.8 % similarity) and Mycolicibacter terrae CIP 104321T (98.8 %) with which strain M1T shared average nucleotide identity of 81.2 % and digital DNA–DNA hybridization similarity of 23.8 %. Strain M1T grew optimally at 0 % NaCl, at pH 6 and at between 30–33 °C. The polar lipid profile of strain M1T consisted of diphosphatidylglycerol, aminophosphoglycolipid, phosphatidylcholine, phospholipid, aminolipid, phosphoglyolipid, phosphatidylglycerol, two unidentified glycolipids and four unidentified lipids. The dominant cellular fatty acids (>10 %) were C16 : 0 and C18 : 1  ω9c and summed feature 7 (C19 : 1  ω7c and/or C19 : 1  ω6c). The DNA G+C content of strain M1T was 69.1 mol%. Based on in silico phylogenomic analysis coupled with physiological and chemotaxonomic characterizations, we classify strain M1T as representing a novel species within the genus Mycolicibacter , for which the name Mycolicibacter acidiphilus nov. is proposed. The type strain is M1T (=MCCC 1H00416T=KCTC 49392T).