The impact of novel bacterial strains and their consortium on diflufenican degradation in the mineral medium and soil

Four novel bacterial strains isolated from agricultural soil were tested for their ability to degrade the persistent herbicide - diflufenican, in a mineral medium and soil. The presence of three potential diflufenican metabolites, 2,4-difluoroaniline, 2-(3-trifluoromethylphenoxy)nicotinamide, and 2-(3-trifluoromethylphenoxy)nicotinic acid, was analysed. The isolated bacterial species were identified by 16S rRNA gene sequencing as Pseudomonas sp. 10Kp8 - A1, Pseudomonas chlororaphis subsp. aureofaciens strain B19 - A2, Pseudomonas baetica strain JZY4-9 - C1, and Streptomyces atratus strain ROA017 - D1. The effect of each isolate and its consortia on diflufenican degradation was compared to control samples without microorganisms. In the mineral salt medium (MSM) and soil, strain D1 showed the highest degradation, reaching 70.1% and 79%, respectively. However, the application of a synthetic consortium of four microorganisms resulted in even higher degradation in both environments, achieving 74.4% and 82.2% in the liquid medium and the soil, respectively. Notably, the microorganisms were able to grow in MSM containing diflufenican at concentrations of 60-220 mg/kg, utilizing it as a source of carbon and energy. The quadruple synthetic consortium holds promise as a bioremediation technique for reducing the contamination of ecosystems by this persistent herbicide. These findings demonstrate the diversity of diflufenican-degrading bacteria in agricultural soil ecosystems and provide a promising new approach for bioremediation of diflufenican and other persistent herbicides in the agricultural soil.