A novel bacterial combination for efficient degradation of polystyrene microplastics

This study aimed to investigate the combined decomposition of polystyrene (PS) microplastics using three bacterial cultures: Stenotrophomonas maltophilia, Bacillus velezensis, and Acinetobacter radioresistens. The ability of all three strains to grow on medium containing PS (Mn 90,000 Da, Mw 241,200 Da) microplastics as the sole carbon source was examined. After 60 days of A. radioresistens treatment, the maximum weight loss of the PS microplastics was found to be 16.7 ± 0.6% (half-life 251.1 d). After 60 days of treatment with S. maltophilia and B. velezensis, the maximum weight loss of PS microplastics was 43.5 ± 0.8% (half-life 74.9 d). After 60 days of treatment with S. maltophilia, B. velezensis, and A. radioresistens, the weight loss of the PS microplastics was 17.0 ± 0.2% (half-life 224.2 d). The S. maltophilia and B. velezensis treatment showed a more significant degradation effect after 60 days. This result was attributed to interspecific assistance and interspecific competition. Biodegradation of PS microplastics was confirmed using scanning electron microscopy, water contact angle, high-temperature gel chromatography, Fourier transform infrared spectroscopy and thermogravimetric analysis. This study is the first to explore the degradation ability of different bacterial combinations on PS microplastics, providing a reference for future research on the biodegradation technology of mixed bacteria.