Selective pressure of arsenic and antimony co-contamination on microbial community in alkaline sediments

As and Sb co-contamination is causing severe concerns worldwide. Although response of microbial community to As and Sb co-contamination has been investigated in the neutral and acidic environments, little is known regarding the selective pressure of As and Sb co-contamination in the alkaline environment. Herein, the response and potential metabolic pathways of the microbial community were determined by combining geochemistry and molecular biological technologies. High As and Sb was introduced into the alkaline sediment by the Sb mine drainage, which was partially adopted in the aquatic environment and resulted in a relatively lower contamination in the downstream sediments. Diversity analyses combined with random forest showed that the microbial richness was significantly damaged and the microbial compositions were dramatically shifted due to the As and Sb co-contamination. Metagenomic analysis shed light on the survival strategies of the microbes under the pressure of As and Sb co-contamination including As(III)/Sb(III) oxidation coupled with denitrification, As(V)/Sb(V) reduction, and As/Sb resistance. The representative microbes were revealed in the sediments with higher (Halomonas) and lower (Thiobacillus, Hydrogenophaga and Flavihumibacter) As and Sb concentration. In addition, ARGs were found to co-occur with metal resistance genes in the bins. These findings elucidated the microbial adaption and survival strategies under the pressure of As and Sb co-contamination, which can provide theoretical guidance for management and bioremediation of As and Sb co-contamination, especially in the alkaline environment.