Diversity of Groundwater Microbial Communities near Sludge Repositories with Different Types and Levels of Pollution

Multicomponent pollution of groundwater with nitrates and sulfates is a common issue associated with mining and ore-processing operations. This work presents the first large-scale comparative study of groundwater microbial communities from six geographically distant sites in the Russian Federation with varying levels of nitrate and sulfate pollution. Based on high-throughput 16S rRNA sequencing data and hydrochemical analysis, a statistically significant influence of the pollution type on the structural and functional diversity of the microbiome was established. Nitrates act as a stimulating factor, increasing alpha-diversity, while sulfates have an inhibitory effect. Principal component and correlation analysis revealed spatial grouping of samples according to the predominant pollution type. Microbiome representatives common to all sites under unpolluted conditions were identified: Bacteroides, Iamia, and Paenibacillus; and under high pollution levels: Acidovorax, Pseudomonas, Sphingomonas, Acinetobacter, and Limnohabitans. Based on the obtained data, it is concluded that representatives of these genera are the most promising and universal for isolation and use in bioremediation.