Analysis of heavy metal-related indices in the Eboling permafrost on the Tibetan Plateau

•Higher levels of most heavy metals were discovered in AL relative to PL.•Metal resistant or DNA repair genes were more abundant in AL relative to PL.•Four heavy metal-resistant phyla were more abundant in AL relative to PL.•C, N, and S cycling genes were less in abundance in AL relative to PL.•Bacteria in AL have evolved an integrated approach to heavy metal tolerance. The relationship between heavy metals and the expression of heavy metal resistance genes (HMRGs) in the active layer (AL) and the permafrost layer (PL) are not well understood, despite being closely linked to the impact of human activity on heavy metal levels and bacterial response to heavy metal stress. Herein, we conducted a metagenomics sequencing analysis to understand how bacteria adapt to such heavy metal stress. We detected higher levels of heavy metals in the AL relative to the PL. Consistent with this, analyses of AL samples revealed the presence of more genes associated with DNA damage repair, DNA recombination, and heavy metal resistance relative to PL samples. Heavy metal-resistant bacterial phyla including Actinobacteria, Acidobacteria, Bacteroidetes, and Cyanobacteria were more abundant in the AL than the PL. At the genera level, we found that bacteria responsible for nitrification, sulfur reduction, and methane oxidation and reduction were less prevalent in the AL relative to the PL. In summary, bacteria in the AL have evolved such that they are able to resist prolonged heavy metal pollution.