AimsTo investigate the effects of long-term acid mine drainage (AMD) irrigation on the change in bacterial community and sulphate-reducing bacteria (SRB) in a paddy soil. Methods and ResultsThe bacterial community structures were investigated using 454 pyrosequencing, and 98931 effective sequences were selected for the bacterial diversity analysis. The known dominant phyla in the paddy soil were Acidobacteria (335%), Proteobacteria (197%), Nitrospira (28%) and Actinobacteria (27%). Higher percentage of Acidobacteria than Proteobacteria was detected. The relative abundances of the dominant bacterial lineages were more significantly correlated with the soil pH, the organic matter and the sulphate than the heavy metals. The diversity of the SRB in the surface paddy soil showed that the uncultured SRB groups might play important roles in paddy soils. The other OTUs mainly belonged to six phylogenetic divisions: Desulfobacca, Desulfovibrio, Syntrophobacter, Desulforhopalus, Desulfarculus and Desulfobulbus. The distribution of the absolute abundance and the relative contribution of the SRB along the vertical soil profile were investigated by RT-PCR assays based on the dsrB gene. The abundance of the dsrB gene copy numbers was up to 192x10(9)copiesg(-1) dry soil, which is slightly higher than the other non-AMD-affected paddy soil. ConclusionsThis study demonstrated that the abundance of SRB is increased by the AMD irrigation while changing the composition and diversity of the bacterial community in the paddy soil. Significance and Impact of the StudyThis is, to our knowledge, the first attempt to characterize and quantify changes in the diversity and distribution of the microbial community and SRB in the long-term AMD-irrigated paddy soil, which will further increase our understanding of the impact of AMD on sulphur biogeochemical cycling in the paddy soil.