Plastics are inexpensive and widely used organic polymers, but their high durability hinders biodegradation. Polystyrene, including expanded polystyrene foam colloquially known as styrofoam, is among the most commonly produced plastics worldwide and is considered to be recalcitrant to microbial degradation. In this study, we assessed changes in the gut microbiome of superworms (Zophobas morio) reared on bran, polystyrene foam, or under starvation conditions over a three weeks’ time period.
Superworms on all diets were able to complete their life cycle to pupae and imago, although superworms reared on polystyrene had minimal weight gains, resulting in lower pupation rates. The change in microbial gut communities from baseline differed considerably between diet groups, with polystyrene and starvation groups characterised by a loss of microbial diversity and the presence of opportunistic pathogens. Inferred microbial functions enriched in the polystyrene group included transposon movements, membrane restructuring, and adaptations to oxidative stress. We detected several encoded enzymes with reported polystyrene and styrene degradation abilities, supporting previous reports of polystyrene degrading bacteria in the superworm gut. By recovering metagenome-assembled genomes (MAGs) we linked phylogeny and functions and identified genera including Pseudomonas, Rhodococcus and Corynebacterium, that possess genes associated with polystyrene degradation.
In conclusion, our results1 provide the first metagenomic insights into the metabolic pathways used by the gut microbiome of superworms reared on polystyrene. Our future plans include the validation and detailed characterisation of the inferred polystyrene degrading enzymes, followed by the development of bio-recycling approaches based on enzymatic plastic degradation.