New isolates of Pseudomonas and Streptomyces as bioremediation tools for aclonifen removal.

Aclonifen is a persistent diphenyl-ether herbicide whose accumulation in agricultural soils poses an increasing environmental challenge. Identifying efficient microbial degraders is therefore essential for developing sustainable remediation strategies. In this study, we demonstrate for the first time the ability of four previously characterized diflufenican-degrading bacterial isolates: Pseudomonas sp. 10Kp8 - A1, Pseudomonas chlororaphis subsp. aureofaciens B19 - A2, Pseudomonas baetica JZY4-9 - C1, and Streptomyces atratus ROA017 - D1, and their four-strain consortium to degrade aclonifen in liquid medium and soil. All strains were able to remove aclonifen as the sole carbon source, achieving degradation efficiencies of 50-60% in mineral salt medium (MSM) after 21 days. Strains A2 and D1 were the most effective and were therefore selected for soil experiments, where the maximum degradation reached 69% for strain D1 by day 28. In both environments, individual strains consistently outperformed the mixed consortium, indicating potential antagonistic interactions within the mixture. By demonstrating that bacteria originally selected for diflufenican removal can successfully target another herbicide, this work introduces a novel and promising biological strategy for the remediation of aclonifen-contaminated environments. These findings broaden the range of microbial candidates for sustainable pesticide remediation and establish a basis for the future development of biological strategies for contaminated agricultural soils.