Nitrate-induced microbial metabolic activation and community composition optimization enhance the anaerobic biodegradation of thiamethoxam

Area of Science:

• Environmental Science
• Microbiology
• Environmental Chemistry

Background:

• Thiamethoxam (THM) is a widely used insecticide with potential aquatic contamination.
• Understanding factors that enhance THM biodegradation is crucial for environmental remediation.

Purpose of the Study:

• To investigate the effect of nitrate on the anaerobic biodegradation of thiamethoxam (THM).
• To elucidate the mechanisms by which nitrate influences THM degradation.

Main Methods:

• Controlled experiments with varying nitrate concentrations.
• Electrochemical analysis (Tafel, EIS).
• Biochemical assays (ETSA, NADH).
• Enzyme activity measurements (NAR, NIR, CAT).
• Macro-transcriptome analysis of microbial communities.

Main Results:

• Nitrate significantly enhanced anaerobic THM biodegradation efficiency.
• THM removal rate increased with nitrate concentration, reaching 85.92% at 200 mg·L^-1.
• Nitrate improved electrochemical activity, electron transfer, extracellular polymer secretion, and enzyme activity.
• Nitrate altered microbial community structure and gene expression, boosting metabolic activity.

Conclusions:

• Nitrate is an effective enhancer of anaerobic thiamethoxam biodegradation in aquatic environments.
• Nitrate promotes THM degradation through improved electrochemical properties, enzyme activation, and microbial community modulation.
• This study offers insights into optimizing bioremediation strategies for pesticide-contaminated waters.