Metatranscriptomic Profiling of Microbial Antimonate Reduction Driven by Photoelectrons from Dissolved Organic Matter in Contaminated Sediments

Microbial antimonate [Sb(V)] reduction in contaminated sediments, driven by photoelectrons generated from dissolved organic matter (DOM) under light illumination, represents a novel natural attenuation pathway. This metatranscriptomic study reveals the active microbial taxa and functional genes involved in this photoelectron-assisted Sb(V) reduction (PESbR) process. Key non-phototrophic genera such as *Sphingomonas*, *Achromobacter*, *Cupriavidus*, and *Bosea* were enriched and exhibited upregulation of Sb(V) respiratory reductases, extracellular electron transfer components, and stress response genes, highlighting a light-dependent microbial mechanism for Sb redox cycling in anoxic environments.