Environmental micro-molar H₂O₂ reduces the efficiency of glyphosate biodegradation in soil

Glyphosate is one of the most widely used pesticides globally. The environmental micro-molar hydrogen peroxide (H₂O₂)-driven Fenton reaction has been reported to degrade herbicides in natural water. However, the impact of micro-molar H₂O₂ (50 μM) on the degradation of glyphosate in soil and glyphosate-degrading bacteria remains unclear. In this study, degradation of glyphosate in the sterilized and unsterilized soil system and MSM medium under micro-molar H₂O₂ was investigated; bacterial diversity, enzyme activity and gene abundance in the soil following micro-molar H₂O₂ addition were also investigated. The results indicated that the addition of micro-molar H₂O₂ facilitated the degradation of glyphosate in a sterilized environment, resulting in a 76.30% decrease in glyphosate within 30 days. The degradation of glyphosate increased by 52.32% compared to the control treatment. However, in an unsterilized environment, the addition of micro-molar H₂O₂ leads to a reduction in the biodegradation efficiency of glyphosate. Bacteria, enzymes and specific genes were found to be affected to varying degrees. Firstly, micro-molar H₂O₂ affects the relative abundance of functional bacteria related to glyphosate degradation, such as Afipia, Microcoleus and Pseudomonas. Secondly, micro-molar H₂O₂ resulted in a decrease in soil phosphatase activity. Thirdly, the expression of resistance genes was affected, particularly the glyphosate resistance gene aroA. The findings presented a novel research perspective on the degradation of soil glyphosate by micro-molar H₂O₂.