Innovative Biotic Symbiosis for Plastic Biodegradation to Solve their End-of-Life Challenges in the Agriculture and Food Industries

Abstract

At present just about 30% of the waste plastic collected is efficiently recycled, while the rest is incinerated, disposed in landfills, or can end up in compost and be released in the environment, inducing a very negative effect on safety and health of flora and fauna. Sustainable management of hardly recyclable plastic waste generated by light weight single use packaging and agricultural films can be improved by applying biotechnological approaches, combining microorganisms, new enzymes, earthworms, and insects to work collaboratively, not only to promote the degradation of these plastics but also to obtain, by-products of the biodegradation process to be valorized as fertilizers, functional polysaccharides, etc. In order to develop a feasible process, mapping and characterization of the most diffused agri-food waste plastic were conducted isolating the main types of plastic involved. Plastic waste in agriculture is mainly constituted by polyethylene (PE) both linear low density (LLDPE) and high density (HDPE), polypropylene (PP) and polystyrene (PS), whereas in food packaging polyethylene is still present together with a large presence of polypropylene, polystyrene and polyethylene terephthalate (PET). Combining plastic presence and availability of organisms for their degradability, representative samples of plastics (PE, PET, PS) were selected for analysis of deterioration and potential subsequent biodegradation by enzymes and organisms. To monitor the plastic degradability by enzymes, and larvae, methods for the plastic analysis were set, outlining some differences in virgin and post consumer plastic in particular after use in agriculture, assessing the possibility to monitor the degradability of plastic with time and different treatments, in particular, some evidence of polyethylene degradability from larvae of Tenebrio molitor was observed.