Temperature Sensitivity of Pyrrhotite-Driven Metavanadate Bioreduction in Groundwater

Pyrrhotite-driven metavanadate [V(V)] bioreduction is a promising green strategy for the remediation of vanadium-contaminated aquifers. However, how this microbially driven process responds to different temperatures remains unclear. Herein, the responses of pyrrhotite-driven V(V) bioreduction to different temperatures ranging from 4 to 45 °C were investigated. V(V) removal first increased and then decreased with increasing temperature, peaking at 35 °C, with the reaction rate constant reaching 0.077 d^-1. V(V) could be reduced to VO₂ precipitates, accompanied by oxidation of S(-II) and Fe(II) to sulfate and Fe(III), respectively. Metagenomic binning revealed that S(-II) oxidation was more sensitive to temperature changes than Fe(II) oxidation for V(V) reducers. Bacteria coupling V(V) reduction with both S(-II) and Fe(II) oxidation (e.g., Ramlibacter sp.) were detected exclusively at 35 °C. The transcription of functional genes (related to V(V) reduction, S(-II) oxidation, and Fe(II) oxidation), electron transport activity and related components all exhibited a temperature-dependent pattern, first increasing and then decreasing, with a peak at 35 °C. This study reveals the temperature sensitivity of pyrrhotite-driven V(V) bioreduction, which is helpful for risk assessment and targeted bioremediation of vanadium contamination under different temperature conditions.