(719g) Polyethylene Deconstruction Initiated By Ldpe-Oxidases from Yellow Mealworm Gut Microbiota

Over 320 million tons of plastics waste enter the environment annually, negatively impacting ecological and human health. Only 14% of plastics produced each year are recycled, with the remainder landfilled, incinerated, or environmentally discarded. Un-recycled plastics wastes represent an under-utilized source of carbon for (bio)manufacturing. Commonly used mechanical recycling strategies are process inefficient, with over 50% of feed lost to the process. Moreover, post-recycled plastics have worsened mechanical properties as a result of melt-blending with each iteration of the recycling process. Alternative chemical recycling approaches operate at high temperatures and pressures and produce unwanted byproducts, hindering economic feasibility. Biological plastics upcycling presents a sustainable and economically viable alternative to utilize waste carbon from plastics by operating at ambient conditions and allowing for product selectivity through metabolic engineering. Insect larvae such as the yellow mealworm biodegrade plastics at rates much faster than soil or marine environments, insinuating that their digestive tract is rich in biological tools that can be used to deconstruct and ultimately upcycle plastics wastes. Current literature suggests that gut microbiota drive plastics deconstruction by insect larvae, but plastic-active enzymes from the gut of the yellow remain elusive. We studied the gut microbiome of the yellow mealworm in order to elucidate the processes through which low-density polyethylene (LDPE), the most abundant plastic waste, is deconstructed. We confirmed the role of the mealworm gut in LDPE deconstruction by observing that gut extracts deconstruct LDPE by three orders of magnitude in the absence of the host. Microbiota isolated from LDPE-enriched mealworm guts initiate deconstruction through biochemical LDPE oxidation. In vitro screening of candidate LDPE-oxidases from these isolates and mealworm gut communities revealed a novel PE-oxidizing enzyme. We identified a sub-clade of PE-oxidases through in vitro screening across the PE-oxidase family. The discovery of LDPE-oxidases permits enzyme engineering efforts for improved PE deconstruction engineering. Moreover, understanding the enzymatic processes for PE oxidation allow for more targeted discovery of downstream enzymatic PE deconstruction steps. Ultimately, PE oxidizing and deconstructing enzymes will coupled with engineered mealworm gut microbial isolates to upcycle plastics waste, tapping into abundant waste carbon to offset petrochemical production for sustainable and economically motivated manufacture of consumer goods.