Plastic waste pollution and its difficult degradation process have aroused widespread concern. Research has demonstrated that the larvae of Tenebrio molitor (yellow mealworm), Galleria mellonella (greater wax moth), and Zophobas atratus (superworm) possess a biodegradation ability for polystyrene (PS) within the gut microbiota of these organisms. In this study, the difference in PS degradation and the changes of the gut microbiota were compared before and after feeding PS. The results showed that superworm had the strongest PS consumption capacity and the highest survival rate during the 30 d experiment period. They all could degrade PS to different degrees. Superworm showed the highest ability to degrade PS into low-molecular-weight substances, while yellow mealworm depolymerized PS strongly by destroying the benzene ring. The changes of the intestinal microbiome caused by feeding PS showed that after ingesting PS, there was a decrease in community diversity in superworm and yellow mealworm, but an increase in greater wax moth. Meanwhile, Enterococcus and Enterobacteriaceae, found in all three species’ larvae upon 20 d of PS feeding, might play an important role in PS degradation. The results will provide more accurate PS degradation comparative data of the three species’ larvae and theoretical guidance for further research on the efficient PS biodegradations.

Polystyrene (PS) is a widely used petroleum-based plastic, that pollutes the environment because it is difficult to degrade. In this study, a PS degrading bacterium identified as Massilia sp. FS1903 was successfully isolated from the gut of Galleria mellonella (Lepidoptera: Pyralidae) larvae that were fed with PS foam. Scanning electron microscopy and X-ray energy dispersive spectrometry showed that the structure and morphology of the PS film was destroyed by FS 1903, and that more oxygen appeared on the degraded PS film. A water contact angle assay verified the chemical change of the PS film from initially hydrophobic to hydrophilic after degradation. X-ray photoelectron spectroscopy further demonstrated that more oxygen-containing functional groups were generated during PS degradation. After 30 days of bacterial stain incubation with 0.15 g PS, 80 ml MSM, 30°C and PS of Mn 64400 and Mw 144400 Da, the weight of the PS film significantly decreased, with 12.97 ± 1.05% weight loss. This amount of degradation exceeds or is comparable to that previously reported for other species of bacteria reported to degrade PS. These results show that Massilia sp. FS1903 can potentially be used to degrade PS waste.