Exploring Hermetia illucens larval gut microbiota for innovative plastic degradation strategies

Plastics are widely employed worldwide, and their accumulation in the environment represents a global concern, as their physicochemical characteristics make them exceptionally persistent and pervasive. Extensive research efforts have focused on identifying microorganisms capable of degrading plastic polymers to implement novel routes for plastic waste valorisation. Several plastic-degrading bacterial species have been isolated from disparate sources, with recent years seeing a significant breakthrough in the biodegradation of plastics by insect-microbiota synergistic action. The mechanical grinding by larval mouthparts and the functional plasticity of the gut microbiota facilitate the degradation of recalcitrant polymers. Among promising insects, Hermetia illucens (Black Solder Fly, BSF) larvae displayed the ability to effectively degrade two types of plastic polymers (i.e., polyethylene and polystyrene) thanks to bacterial communities inhabiting their midgut. Our research aims to unveil the potential of H. illucens larvae as a bio-incubator for bacteria carrying PET-degrading enzymes. Efforts were devoted to i) monitoring the growth and development of H. illucens on PET-containing diets, ii) studying larval physiological responses to oxidative stress and damage triggered by PET exposure, and iii) characterizing shifts in microbial community composition in different larval gut regions caused by PET ingestion. The possibility of exploiting this insect for degrading or bioconverting plastic waste, as well as a source of promising plastic degrading enzymes, will widen the horizons of their biotechnological applications.