Amycolatopsis acidiphila sp. nov., a moderately acidophilic species isolated from coal mine soil.

Little is known on members of the genus Amycolatopsis inhabiting acidic habitats. In this study, a moderately acidophilic Amycolatopsis strain, designated 2-5T, was isolated from coal mine soil, and subjected to a polyphasic taxonomic characterization. Analysis based on 16S rRNA gene sequences indicated that the strain was most closely related to the type strain of Amycolatopsis bartoniae, sharing 99.30 % similarity, while similarity to all other Amycolatopsis species was less than 97 %. The DNA-DNA relatedness between the new isolate and the type strain of A. bartoniae was 56.5±0.7 %. The optimal pH range of the isolate for growth was 5.5-6.0, but growth also occurred at pH 4.5 and 7.5. The isolate tolerated up to 6 % (w/v) NaCl (optimum, 0 %), and the temperature range for growth was 15-40 °C (optimum, 30 °C). The isolate was able to utilize most substrates tested for sole carbon sources, showing its metabolic versatility. The isolate exhibited antimicrobial activity against Serratia marcescens and weak antifungal activity against Fusarium proliferatum. The chemotaxonomic profiles of strain 2-5T included polar lipids containing phosphatidylethanolamine, phsphatidylmethylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol dimannosides, fatty acids containing C17 : 1ω6c and iso-C16 : 0 as the major components, MK-9(H4) as the predominant menaquinone, and meso-diaminopimelic acid and arabinose, galactose, glucose and ribose as the diagnostic diamino acid and sugars in the cell wall. The combined phenotypic, chemotaxonomic and genotypic analyses clearly indicated that the isolate merits recognition as represnting a novel species of Amycolatopsis, for which the name Amycolatopsis acidiphila sp. nov. is proposed. The type strain is 2-5T (=KCTC 39523T=JCM 30562T).