Investigating the biodegradation and fate of plastics in the gut of xylophagous insect larvae

ongoing

The recalcitrance of plastics leads to their accumulation in the environment, where physical deterioration in absence of degradation is causing widespread pollution. Microplastics have been found to enter the food chain and to bio accumulate with hitherto unknown long-term health effects, making plastic pollution one of the major environmental problems of our time. In recent years, a plethora of plastic degrading microorganisms and enzymes have been reported, however their degradation efficiencies, especially for conventional plastics, are often underwhelming. Enzymes capable of plastic degradation share a close homology to enzymes involved in the degradation of natural plant derived polymers, such as esterases, cutinases, lipases. It is therefore no surprise that most plastic degrading microorganisms and enzymes are found in the soil environment and compost, where plant litter is a dominant carbon source. Recently, microorganisms inhabiting the guts of xylophagous insect larvae were reported to degrade highly recalcitrant plastics such as polyethylene, polystyrene and polyurethane. However, evidence of this degradation remains scarce and to date few enzymes capable of degrading these polymers could be confirmed. in this regard, xylophagous insect larvae harbour much untapped potential for the discovery of unknown plastic degrading microorganisms and enzymes that could help mitigate plastic pollution. This project will benefit from my previous experience with stable isotope probing, sequencing analysis and plastic degradation by using carbon-13 labelled plastics to investigate plastic fate and degradation in the gut of xylophagous insect larvae. Cryosectioning of the larval gut and state-of-the-art imaging technologies will be used to study plastic fate. Stable isotope probing coupled with metagenomics and proteomics will then identify genes and enzymes responsible for plastic degradation and their function will be confirmed in vitro through heterologous expression.