Auxiliary voltage enhanced microbial methane oxidation co-driven by nitrite and sulfate reduction.

Area of Science:

• Environmental Microbiology
• Biotechnology
• Electrochemistry

Background:

• Methane oxidation is crucial for mitigating greenhouse gas emissions.
• Coupling methane oxidation with sulfate and nitrite reduction offers a promising bioremediation approach.
• Bioelectrochemical systems provide a controllable platform for enhancing microbial processes.

Purpose of the Study:

• To investigate methane oxidation driven by sulfate and nitrite reduction using auxiliary voltage in single-chamber bioelectrochemical reactors (EMNS).
• To determine the optimal voltage for maximum methane conversion efficiency.
• To identify the microbial communities involved and elucidate the oxidation and reduction pathways.

Main Methods:

• Utilized single-chamber bioelectrochemical reactors (EMNS) with applied auxiliary voltage.
• Quantified methane removal rates and identified oxidation products (CO2, methanol).
• Analyzed microbial populations using qPCR and high-throughput sequencing, identifying key methanotrophs and bacteria involved in sulfate and nitrite reduction.

Main Results:

• Methane oxidation was simultaneously driven by sulfate and nitrite reduction, enhanced by auxiliary voltage.
• The maximum methane removal rate of 8.05 mg L⁻¹ d⁻¹ was achieved at 1.6 V.
• Identified key microbial players including Methylocaldum sp., Methylocystis sp., Methylobacter sp., M. oxyfera, Ignavibacterium sp., and Desulfovibrio sp.

Conclusions:

• Auxiliary voltage significantly enhances methane oxidation coupled with sulfate and nitrite reduction in EMNS.
• The study elucidated the roles of specific microbial groups in methane oxidation, denitrification, and sulfate reduction.
• This bioelectrochemical approach presents an effective strategy for methane mitigation and pollutant removal.