A novel Bacillus velezensis strain with the ability to simultaneously biodegrade polystyrene microplastics and fungicide carbendazim

In this study, a novel bacterial strain, M1, capable of degrading both polystyrene (PS) microplastics and carbendazim, was isolated from soil heavily contaminated with microplastics and fungicide carbendazim, and was identified and determined to be Bacillus velezensis. During the 60-day cultivation period, degradation experiments with single pollutants demonstrated that, at a concentration of 1000 mg/L, the strain achieved mass reduction efficiency of 10.8 ± 0.95 % for PS microplastics and 56.64 ± 0.60 % for carbendazim. Remarkably, under co-exposure conditions with both pollutants (1000 mg/L each), attaining mass reduction efficiency of 6.60 ± 0.85 % for PS microplastics and 34.70 ± 2.52 % for carbendazim respectively. After 60 days of biodegradation, scanning electron microscopy (SEM), water contact angle (WCA), high-temperature gel chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) confirmed the biodegradation of PS microplastics by Bacterium M1 under different conditions. The biodegradation of carbendazim by bacteria under different conditions was confirmed by high performance liquid chromatography (HPLC), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) analyses. This study reports for the first time a novel bacterial strain capable of simultaneous degradation of both PS microplastics and carbendazim, providing a new approach to address composite organic pollution in the environment.