| Microbial oxidation of sulfide minerals produces large amounts of sulfuric acid. Mine waste runoff acidified by this H2SO4 is called acid mine drainage (AMD). AMD pollutes the ground and surrounding waters creating a perilous situation for the native flora and fauna. At a pH of ∼2, this extreme environment is the habitat to a variety of acidophilic microorganisms. AMD samples were collected from three flooded tailings sites. Through traditional recovery methods, microorganisms were isolated on six selective solid media. Subsequent to isolate purification, morphological and nutritional studies were conducted in order to determine the populations of acidophiles indigenous to each site. Iron-oxidizing autotrophs were isolated from two of the three sites sampled. Studies concluded that each of the 12 isolates were the iron-oxidizer Acidithiobacillus ferrooxidans. Sulfur-oxidizing isolates of Acidithiobacillus thiooxidans were recovered from each site. The first site yielded 7.1 x 103 CFU/mL, the second had 1.5 x 102 CFU/mL and the third had 1.3 x 10 2 CFU/mL. Acidiphilium acidophilum, a facultative heterotroph, was also isolated from each site. Counts of 2.5 x 10 4 CFU/mL, 3.9 x 104 CFU/mL and 2.1 x 10 2 CFU/mL were recovered from the samples. The counts of heterotrophic acidophiles isolated from these environments ranged from 2.0 x 10 2 to 1.4 x 104 CFU/mL. The species all belonged to the genus Acidiphilium. The bacterial populations recovered from these sample sites were typical of AMD environments. |
