Response of the yellow mealworm (Tenebrio molitor) gut microbiome to diet shifts during polystyrene and polyethylene biodegradation

Plastic biodegradation by mealworm is regarded as an emerging strategy for plastic disposal. In this study, the polystyrene (PS) and low density polyethylene (LDPE) degradation efficiency by yellow mealworms (Tenebrio molitor larvae) supplemented with bran and the effects of plastics on the gut core microbiome were explored to construct a circular and continuous reactor for plastic biodegradation in the future. The gut microbiome was also investigated with dietary shift to explore the relationship between specific diets and gut microbes. The bran plus plastic (7:1 ratio, w/w) co-diet contributed to the mealworm survival and growth. The formation of - C=O- / -C-O- groups in the plastic-fed mealworms frass represented the oxidation process of plastic biodegradation in the mealworm gut. The changes in molecular weights (Mw, Mn and Mz) of residual PS and LDPE in mealworms frass compared with that of PS and PE feedstock confirmed the plastic depolymerization and biodegradation. Lactobacillus and Mucispirillum were significantly associated with PE + bran diet compared to bran diet and PE diet, representing the response of mealworm gut microbiome to the bran and plastic mixture was distinguished from either bran or plastics alone. The gut microbiome changed substantially with the diet shift, indicating that microbial community assembly was a stochastic process and diverse plastic-degrading bacteria might occur in the mealworm gut.

Automated summary

The study found that the yellow mealworms supplemented with bran had higher degradation efficiency of polystyrene and low density polyethylene, and the addition of bran and plastic mixture in the diet contributed to the survival and growth of the mealworms. The gut microbiome of the mealworms was closely associated with the diet type, playing an important role in the oxidation process and degradation of plastics.