Mining-Related Multi-Resistance Genes in Typical Nonferrous Metal(Loid) Tailing Impoundments Under Bio-Restoration

Abstract

Tailing impoundments threaten human health because they are reservoirs of multi-resistance. Potential co-selection of antibiotic resistance genes (ARGs) metal(loid) resistance genes (MRGs) during bio-restoration have been poorly investigated. In Guangxi metal(loid)s-rich nonferrous tailings, where a bio-restoration based on sulfate-reducing bacteria (SRB) addition was implemented, the metal(loid)s (including As, Cd, Fe, Pb, Sb, and Zn) content was the main factor driving the microbial community organization. Based on shotgun metagenomic analysis, the relative abundance of sulfonamide-related ARGs decreased, but those related to bacitracin and chloramphenicol increased according to metal(loid)s content. Thiobacillus  and Sphingomonas  were the main genera carrying the bacA  and mexEF  resistance operons, and, together with Sulfuricella , were also found as main genera carrying MRGs. The added SRB strains, Desulfosporosinus  and Desulfotomaculum , and the acidophilic strain Acidiphilium  significantly contributed to the distribution of sul  genes, while Thiobacillus , Sphingomonas , Sulfuricella , and Meiothermus  genera significantly contributed to the distribution of MRGs. Additionally, ARGs ( mexNW , merD , sul  and bla ) and MRGs ( czcABCR  and copRS genes) were found on the same contig, revealing the co-selection of ARGs and MRGs. Co-selection of ARGs and MRGs should be considered for the implementation of bio-restoration processes as they can impact human health. The study also shows the involvement of iron metabolism via  Feo -like genes in bio-restoration process, providing new insights, useful for the management of tailings’ bio-restoration.

Keywords: Microorganisms, antimicrobial resistance, Metal resistance, Co-selection, Tailings impoundments