Effects of Copper Concentration Gradient on the Evolution Direction of Soil Microbial Community Around Active Lead-Zinc Tailings

Abstract

Mining activities will produce a large amount of active tailings accumulation, resulting in heavy metal pollution, which can greatly change the evolutionary direction of surrounding soil microorganisms and affect the biogeochemical cycle process. However, little is known about the effects of heavy metal concentration gradients on microbial communities and the mechanisms of microbial community evolution in active tailings environments. Herein, we collected soil samples around active lead-zinc tailings including uncontaminated and contaminated soils, by 16S rRNA gene sequencing to gain insight into soil microbial community structure and evolutionary direction under copper (Cu) concentration gradient stress. Investigation of tailings and surrounding soil found that the Cu concentration gradient was the main factor responsible for the significant differences in microbial community diversity and composition. Actinobacteria, Proteobacteria, Acidobacteriota dominated the original microbial community and continued changes in the microbial community were observed along the copper concentration gradient, revealing that copper induced the microbial community dominated by Proteobacteria to the Thermoplasma and Methylation bacteria-dominated microbial community evolution. We also found that 10 - 30 mg/Kg Cu can promote the abundance of microbial community but 50 mg/Kg Cu greatly reduces its abundance, which observed across different microbial phyla. Co-occurrence network analysis and functional prediction were performed, and a hypothesis was proposed that the microbial community could resist heavy metal stress by adjusting metabolic strategies. This study deepened the understanding of heavy metals contamination in an active tailings, and the microbial community succession with Cu concentration gradients and provided theoretical guidance for bioremediation of heavy metals pollution from active tailings.

Keywords: Copper concentration gradient, soil microbial community, evolution direction, typical active tailing