Lakes in arid northwestern China are valuable freshwater resources that drive socioeconomic development. Microbial communities play an important role in the element biogeochemical cycle. Hence, it is important to understand the relationship of bacterial community composition and functional genes (e.g. metal resistance genes, MRGs) with the environmental pollutants.

In order to quantify the occurrence and accumulation of heavy metals and identify the composition of microbial communities in water, sediment and biofilm, a research team led by Dr. SONG Wenjuan from the Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences investigated the Bosten Lake and Ebi Lake from arid northwestern China.

The study, published in Environmental Pollution, was also aimed to compare the distributions of MRGs in water, sediment and biofilm and to examine the correlations between heavy metals, bacterial community composition and MRGs.

Research results showed that the mercury resistance gene subtype merP had the greatest average abundance (4.61×10^-3 copies per 16S rRNA) among all the samples, followed by merA and merC.

The high abundance of merA in the pelagic zone rather than in benthic sediment suggested that the pelagic microbial community was important in mercury reduction. Proteobacteria were the main phylum found in the microbial communities in all samples.

However, microbial communities in most of the water, sediment and biofilm samples had different compositions, indicating that the habitat niche plays an important role in shaping the bacterial communities in lakes. The microbial community, rather than the heavy metals, was the main driver of MRG distribution.

The abundances of some bacterial genera involved in the decomposition of organic matter and the terrestrial nitrogen cycle were negatively correlated with heavy metals. This result suggests that metal pollution can adversely affect the biogeochemical processes that occur in lakes.

This study provides a comprehensive understanding of the bacterial communities and MRGs in different environments.