Phylogenetic Analysis of Bacterial Populations Found in Groundwater and an Acidic Stream Draining from an Abandoned Coal Mine.

Abstract

A phylogenetic analysis of heterotrophic bacterial populations inhabiting streams and groundwater contaminated by acid mine drainage (AMD) was conducted. The samples were collected from sites around an inactive underground Dae-Sung coal mine at Keumsan, Korea. The investigation showed pigment-forming bacteria to be the major strains inhabiting the pollutant, accounting for up to approximately 50% of all isolates. Twenty-six pigment-forming bacteria were isolated and their taxonomic characteristics determined by phenotypic, chemotaxonomic and phylogenetic analyses. Based on a phylogenetic analysis using 16S ribosomal RNA gene nucleotide sequences, these isolates were found to fall within four major phylogenetic groups: a, b, and g subdivisions of Proteobacteria; and low-G+C gram-positive bacteria. The a-Proteobacteria were further separated into a-1, a-2 and a-4 subclasses. Many isolates from the polluted stream (site P5) and groundwater (site G) were identified as Sphingomonas of the Proteobacteria a-4 subclass. Because strains P5-21 and P5-11 appeared to be novel species within the genus Sphingomonas, the discussion was focused on their taxonomy as well as abundance in the polluted regions.