soil metagenome Raw sequence reads

Arsenite (As(III)) oxidation(AsO)-dependent chemolithoautotrophic diazotrophs (AsODs) play an important role in providing bioavailable nitrogen (N) and organic carbon and transporting of arsenic (As) speciation in As-contaminated oligotrophic environments, but the understanding of microorganisms responsible for AsO dependent BNF (AsON) has been limited. In this study, DNA-stable isotope probing (DNA-SIP) and metagenomics analysis were combined to identify potential AsODs and predict their metabolic potentials. Biological N fixation (BNF) was exclusively observed in the soils and sediments amended with As(III), whereas no apparent BNF was detected in the cultures without As(III). The increasing abundance of the nitrogenase gene (nifH) and AsO gene (aioA) suggests that AsON process was catalyzed by microorganisms harboring nifH and aioA genes. DNA-SIP incubation demonstrated that Thiobacillus spp. and Anaeromyxobacter spp. were putative AsODs. The metagenomic analysis further revealed that they contained genes responsible for BNF, AsO and CO2 fixation, supporting their capability for AsON. These observations suggested the occurrence of AsON in various As-contaminated habitats. A number of putative AsODs (i.e., Thiobacillus spp. and Anaeromyxobacter spp.) were reported here, which expands our current knowledge regarding the diversity of AsODs.