Synergistic glyphosate degradation in a rice-duckweed-microbe system: Mechanistic insights and sustainable remediation potential

Glyphosate pollution in rice paddies poses serious environmental and food safety concerns. This study evaluated a rice-duckweed (Oryza sativa-Spirodela polyrhiza) system for glyphosate removal and residue reduction. Four treatments, duckweed alone (F), rice-duckweed with microbes (RP), rice-duckweed with sterilized soil (SRP), and rice alone (R), were examined using HPLC-MS/MS, enzyme assays, and 16S rRNA sequencing. The RP system achieved up to 90 % glyphosate removal and significantly reduced residues in rice tissues compared with R (p < 0.05). Lower antioxidant enzyme activities and malondialdehyde levels indicated alleviated oxidative stress in rice. Microbial analysis revealed enrichment of Proteobacteria, Thiobacillus, and Desulfitispora, indicating active glyphosate degradation. Four isolate, Priestia megaterium, Bacillus proteolyticus, Paenarthrobacter ureafaciens, and Bacillus siamensis, exhibited strong degradation ability, and their consortium (Syn-4) achieved 87 % removal with efficient aminomethylphosphonic acid (AMPA) turnover. The results demonstrate that rice-duckweed-microbe interactions synergistically enhance glyphosate degradation, providing a sustainable approach for herbicide remediation in paddy ecosystems.