Succession of AMD bacterial communities under high Fe3+ concentration

摘要

In acid mine drainage ( AMD) , the bacteria rapidly oxidize ferrous ions to produce a large amount of ferric ions in the surrounding AMD environment. However, the importance of ferric ions in the bacterial metabolism and succession of microbial community structure has attracted little attention. The aim of the investigation was to study the succession of bacterial communities under various Fe3 + concentrations by Amplified Ribosomal DNA Restriction Analysis (ARDRA) method. The result showed that the growth of acidophiles inhabited in the AMD environments was remarkably influenced by Fe + concentration. A total of 8 operational taxonomic units ( OTUs) were recovered in two samples (JX and FS) , when they were cultured in media with increased Fe3+ concentration. These OTUs were affiliated to a-Proteobacteria ( mainly Acidiphilium sp. ) , -y-Proteobacteria ( mainly A. ferrooxidans) , Nitrospira ( mainly Leptospirillum sp. ecies) , and Actinobacteria ( Ferrimicrobium acidophilum). The succession of bacterial community indicated the existence of a competitive relationship between A. ferrooxidans and Leptospirillum-like bacteria. A. ferrooxidans grew initially in the media of high Fe2+ but low Fe3 + concentrations. The growth rate of A. ferrooxidans was found significantly inhibited at high Fe3+ concentration. For Leptospirillum-like species, the growth rate was less sensitive to Fe + and their iron-oxidizing ability was not significantly affected. When the sample FS was cultured in the medium with 12. 5 g/L of ferric ions, a bacterium which had 99% phylogenetic similarity to Ferrimicrobium Acidiphilum became the most predominant species.