Pesticide tolerant rhizobacteria isolated from rice (Oryza sativa) overcomes the effects of salt and drought stress in pesticide contaminated condition

Aims The overuse of pesticides is harmful to soil ecosystems and human health. Understanding the role and activities of rhizobacteria in response to pesticide residues and abiotic stress challenges is critical for green and sustainable agriculture. This study isolated indigenous rhizobacteria from the rice rhizosphere for their plant growth-promoting abilities and tolerance to pesticide, salinity, and drought stress. Methods Selection, screening and testing the effect of pesticide tolerant rhizobacteria on drought and salinity stress under mancozeb, 2,4-D and copper hydroxide conditions. Identified isolates based on 16S rRNA gene sequencing. The degradation of 2,4-D was analyzed by HPLC, while mancozeb residue was determined by titration. Results Enterobacter cancerogenus E50S2-4, Bacillus amyloliquefaciens E50S2-3, Klebsiella quasipneumoniae M50R2-3, and Bacillus velezensis M100S1-4 were identified as plant growth promoting rhizobacterial strains that tolerate mancozeb, 2,4-D and copper hydroxide, while producing proline, exopolysaccharides, biofilm and 1-aminocyclopropane-1-carboxylate deaminase under pesticide conditions. These rhizobacteria thrived at NaCl 12 dS m(-1) and 20% PEG, despite exposure to 2,4-D herbicide. The study presented kinetic growth data for rhizobacteria in a pesticide conditions, demonstrating their ability to grow and resist the presence of mancozeb and 2,4-D. Bacillus amyloliquefaciens E50S2-3 showed outstanding results by reducing 43.60% and 39.92% of 2,4-D and mancozeb residues, respectively, while Enterobacter cancerogenus E50S2-4 resulted in a 40.91% reduction of mancozeb. Conclusions This study highlights the ability of rhizobacteria to tolerate the combination of salinity, drought, and pesticides. The results suggest that PGPRs may play a role in the mitigation and degradation of 2,4-D and mancozeb residues in soil.

Automated summary

This study isolated and tested pesticide-tolerant rhizobacteria from the rice rhizosphere. These strains were found to produce beneficial substances for plant growth and were able to grow and resist in the presence of 2,4-D and mancozeb residues. In particular, the E50S2-3 strain showed outstanding results in reducing these residues.