(164as) Plastics Degradation By the Yellow Mealworm Gut Microbiota and Associated Enzyme Studies

Plastics waste is accumulation is a worsening problem due to global reliance on low cost and high durability plastics. Over 7 billion tons of plastics waste have accumulated since 1950. Roughly nine percent of plastics are recycled globally, with economic incentive being a key inhibitor to increasing recycling throughput. Current plastics waste management techniques (incineration, mechanical recycling, and chemical recycling) lack economic viability due to the need for expensive catalysts, high operating conditions, pretreatment, and mechanical sorting. Biodegradation presents a sustainable and economic upcycling solution by eliminating the mentioned cost barriers. The microbiota of insect larvae, namely the yellow mealworm (T. molitor), have recently been identified as a platform for plastics biodegradation by demonstrating improved plastics consumption rate over reported microorganisms, which insinuates microbial community synergies.

Only a small fraction of the total number of microorganisms from the guts of plastic-fed mealworms have been isolated and shown to degrade plastics. There exists a knowledge gap and an opportunity to discover plastics-degrading organisms and associated enzymes from the yellow mealworm gut microbiome. In this work, we aim to address this knowledge gap by isolating plastic-degrading organisms from yellow mealworms, by using bioinformatic analyses to determine microbial species and genes prevalent in plastic-fed mealworms, and by doing early work in extracting plastic-degrading enzymes.

Isolates were extracted from dissected mealworm guts and screened for growth with polyethylene as the sole carbon source in order to discover microbes capable of degrading plastics. A subset of unique isolates was discovered, and plastics degradation is indicated by growth on plastic-containing media and scanning electron microscopy (SEM). Metagenomic data provided by the Joint Genome Institute (JGI) from the gut microbiota of worms fed Polystyrene (PS), Low-Density and High-Density Polyethylene (LDPE, HDPE), and Polypropylene (PP) were analyzed to determine microbial taxa and associated genes prevalent to the degradation of each plastic.

Early-stage enzyme studies of supernatant and lysis solutions from microbial isolate cultures were performed on fluorescent LDPE particles to demonstrate in vitro activity. Shotgun proteomics coupled with mass spectrometry and fast protein liquid chromatography (FLPC) were used to identify proteins important for plastics degradation. The results from these studies indicate the presence of plastics degrading enzymes from the plastics-degrading isolates.

The findings detailed in this work will allow for further studies elucidating the degradation pathways of plastics-degrading organisms. Discovering these pathways will allow for the isolation and purification of key enzymes in plastics degradation processes and provide the potential to engineer these pathways for enhanced plastics degradation and upcycling. In parallel, synthetic microbial consortia or synthetic enzyme cascades can be developed in order to mirror the plastics degradation present in the gut of T. molitor outside of the worm. The work in these studies and subsequent future studies can have the potential to be scaled for large-scale plastics upcycling in a bioreactor with conditions emulating and improving upon those present in the gut of the yellow mealworm.