Diversity Analysis of an Extremely Acidic Soil in a Layer of Coal Mine Detected the Occurrence of Rare Actinobacteria

Studies that explore the diversity of microorganisms in the unusual (extreme) environment become more common in the recent studies. Our research aims to predict the diversity of bacteria that inhabit an extreme environment, a coal mine soil with pH of 2.93. Soil samples were collected from the soil at a depth of 12 meters from the surface, which is a clay layer adjacent to a coal seam in Tanjung Enim, South Sumatera, Indonesia. A culture-independent method, the polymerase chain reaction based denaturing gradient gel electrophoresis, was used to amplify 16S rRNA gene to detect the viable-but-unculturable bacteria. Results showed that some OTUs have never been found in the coal environment, and they have phylogenetic relationships to the rare actinobacteria, that are Actinomadura, Actinoallomurus, Actinospica, Streptacidiphilus, Aciditerrimonas , and Ferrimicrobium . Accordingly, the highly acidic soil in the coal mine is a source of rare actinobacteria that can be explored further to obtain bioactive compounds for the benefit of biotechnology.