Defunct gold mine tailings are natural reservoir for unique bacterial communities revealed by high-throughput sequencing analysis.

Mine tailing dumps are arguably one of the leading sources of environmental degradation with often both public health and ecologically consequences. The present study investigated the concentration of heavy metals in gold mine tailings, and used high throughput sequencing techniques to determine the microbial community diversity of these tailings using 16S rRNA gene based amplicon sequence analysis. The concentration of detected metals and metalloids followed the order Si > Al > Fe > K > Ca > Mg. The 16S rRNA gene based sequence analysis resulted in a total of 273,398 reads across the five samples, represented among 7 major phyla, 41 classes, 77 orders, 142 families and 247 major genera. Phylum Actinobacteria was the most dominant, followed by Proteobacteria, Firmicutes, Chloroflexi, Cyanobacteria, Bacteroidetes, Acidobacteria and Planctomycetes. Redundancy analysis (RDA) and pairwise correlation analysis positively correlated the distribution of Alphaproteobacteria and Gammaproteobacteria to Al and K; Actinobacteria to Cr and Chloroflexi to Si. Negative correlations were observed in the distribution of Bacteroidetes with respect to As concentrations, Actinobacteria to Al, and Alphaproteobacteria and Gammaproteobacteria to high As and Te content of the soils. Predictive functional analysis showed the presence of putative biosynthetic and degradative pathways across the five sample sites. The study concludes that mine tailing sites harbour diverse and unique microbial assemblages with potentially biotechnologically important genes for biosynthesis and biodegradation.