Biodegradation of polystyrene by bacteria isolated from the yellow mealworm (Tenebrio molitor) gut

Polystyrene (PS) is commonly used in human production and life because it is chemically stable and easy to produce and process. However, PS is difficult to degrade naturally, which leads to environmental pollution and threats to human and animal health. In this study, two bacterial strains known to degrade PS, Klebsiella sp. WJ2020 and Cellulosimicrobium sp. WJ2025 were isolated from Tenebrio molitor intestines. Both strains could grow with PS as their sole carbon source and caused weight loss of 4.35% and 6.93% to the PS films over a 60 day-incubation, respectively. The number-average molecular weights of the PS after incubation with the strains also decreased by 4.85% and 10.48%, respectively. The surface of the PS films had a significant lamellar etching after microbial action. Moreover, WJ2020 and WJ2025 imparted more oxygen to the PS surface and formed additional hydroxyl groups, which led to a decrease in the hydrophobicity of the PS film surface. The roughness of the degraded PS films was increased compared to the PS films without bacterial treatment. Results from this study provide a potential solution for the natural biodegradation of PS while adding to the scientific knowledge of the function of the gut microorganisms of the yellow mealworm.