PRJNA719005
16S rRNA gene amplicon sequencing of incubated sediments from an As-contaminated aquifer in Hanoi (Vietnam)
Although arsenic (As) groundwater contamination in South and Southeast Asia is a threat to human health, mechanisms of its release from sediment to groundwater are still not fully understood. In these aquifers, Fe(III) minerals are often the main hosting phases for As and their stability is crucial for As mobility. Recently, a new mechanism for As mobilization into groundwater was proposed with methane (CH4) serving as an electron donor for microbially-mediated reductive dissolution of As-bearing Fe(III) minerals. To provide evidence for the occurrence of Fe(III)-coupled methanotrophy, we incubated sediments from an As-contaminated aquifer in Hanoi (Vietnam) anoxically with isotopically labeled 13CH4. The microbial community at the end of the incubation was dominated by archaea affiliating with Candidatus Methanoperedens, implying its contribution to Fe(III)-dependent CH4 oxidation. These results suggest that methanotrophs can contribute to dissolution of As-bearing Fe(III) minerals, which eventually leads to As-release into groundwater.