Changes in microbial community structure during the biooxidation of iron and inorganic/organic sulfur provide prediction of acid mine drainage from coal spoil

Abstract

To thoroughly investigate the formation mechanism of acid mine drainage (AMD) from coal mine spoil, this study conducted microbial shake flask experiments on gangue possessing inorganic and organic sulfur to predict the future generation of AMD. The results revealed that microbial-mediated sulfur oxidation effectively lowered the pH of leachate and increased metal ion and sulfate concentrations. The oxidation of pyrite sulfur and thiophene sulfur contributed to 70 % and 30 % of the total acid production, respectively, highlighting the importance of both processes in coal mine acidification. The abundance and diversity of the microbial community increased, with "new" iron and sulfur oxidizing bacterial species during acidification, with "new" iron and sulfur oxidizing bacterial species, such as Sulfobacillus sp. and Acidibacillus sp., emerging and constituting approximately one-third of the bacterial population. These bacteria survived desiccation and proliferated faster than A. ferrooxidans YQ-N3 when conditions favored growth.

Keywords: Acidification; Acidithiobacillus ferrooxidans; Coal gangue; Microbial community; iron and sulfur transformation.