Microbe–arsenic interactions in groundwater: From community evolution to functional regulation

Arsenic (As) enrichment in groundwater is a global environmental and public-health crisis. Here we investigate potential microbe-arsenic associations in a representative groundwater system from the Kuitun River Basin, a typical arid, high-As region in Xinjiang, China. Based on 16S rRNA gene amplicon sequencing and functional inference (PICRUSt2, FAPROTAX, BugBase) of 15 groundwater samples (8 high-As, 7 low-As), we observed that As concentration is associated with a statistically significant but weak‑to‑moderate taxonomic divergence (ANOSIM R = 0.2012, p = 0.025) in a Proteobacteria-dominated community, with Pseudomonas prevailing in the low-As group and Acinetobacter enriched under high As. Predicted functional profiles suggest that high-As conditions may suppress community metabolic potential while showing trends toward enrichment of sulfur respiration and sulfate respiration. The inferred abundances of K02014 and K03088 were negatively correlated with As concentration. Phenotype prediction indicated enrichment of anaerobic metabolism and Gram-positive traits in the high-As group. Together, these results support a hypothesized framework of "Environmental selection–Functional inference–Geochemical feedback", through which microbial communities may potentially influence As cycling.