iron-metabolizing communities in soils contaminated by acid mine drainage from an abandoned coal mine in Southwest China Raw sequence reads. iron-metabolizing communities in soils contaminated by acid mine drainage from an abandoned coal mine in Southwest China

Acid mine discharge (AMD) has been demonstrated to have significant impacts on microbial community composition in the surrounding soil environment. However, their effect on adjacent soil has not been extensively studied. In this study, the microbial community composition of twenty AMD-contaminated soil samples collected from an abandoned coal mine along the pollution gradients was characterized using high-throughput sequencing. All samples were characterized as extremely low in pH (< 3) and relatively enriched in Fe species. The dominant phylotypes were belonging to the genera Ochrobactrum, Acidiphilium, Staphylococcus, Brevibacterium, and Corynebacterium. Canonical correspondence analysis results revealed that pH and levels of Fe species were strongly correlated. Co-occurrence network analysis revealed that Aquicella, Acidobacteriaceae, Ochrobactrum, Enhydrobacter, Sphingomonas, and Legionellales correlated with other taxa closely, demonstrating their importance in the microbial interactions. It is interesting to find that most of the abundant taxa have been reported as acidophilic Fe-metabolizing bacteria. Hence, a subnetwork co-occurring analysis and a phylogenetic tree relating to microbial taxa responsible for Fe-oxidation and Fe-reduction were constructed and described. The biotic interaction results showed that Dechloromonas exhibited densely connections with Fe(III)-reducing bacteria of Comamonas, Burkholderia, Shewanella, Stenotrophomonas, Acidithiobacillus, and Pseudomonas. These results confirmed that Fe-metabolizing bacteria could inhabit in soils contaminated by AMD, and potentially played an important role in the Fe biogeochemical cycling.