Tenebrio molitor Could Be an Efficient Pre-Treatment Bioagent for Polystyrene Initial Deterioration and Further Application of Pleurotus eryngii and Trametes versicolor in Microplastic Biodegradation

Plastic is a major organic pollutant globally but has only recently been recognized for its recalcitrant nature and resistance to degradation. Although vast amounts of plastic debris are overwhelming the planet, the search for solutions to its degradation has only recently begun. One of the most well-known agents of plastic biodegradation is the larvae of Tenebrio molitor, which can alter the structure of polymers like polystyrene. However, while this insect can cause deterioration, its frass, which still consists of polystyrene microplastics, remains a problem. We investigated whether this frass could be further degraded by strains of white rot fungi, specifically Pleurotus eryngii and Trametes versicolor. We introduced two PS derivatives (styrofoam and stirodure) to the fungi in liquid media and evaluated oxidative metabolism enzymes (laccase, Mn-peroxidase, lignin-peroxidase) activities, and the phenolic products of the potential aromatic polymer degradation in the media. Finally, we evaluated FTIR spectra to determine if we could detect changes in polystyrene molecule degradation. Both fungi produced high amounts of enzymes, particularly when the polystyrene was present. Large quantities of phenolic substances were simultaneously detected, some associated with polystyrene degradation. FTIR spectra of different polystyrene products confirmed species-specific mechanisms for their degradation by experimental fungal strains.