Microbial Consortium for Mixed Waste Plastic Degradation — 2a — Chirag Abrol¹, Kritika Thakur², David R. Salem², and Rajesh K. Sani^1,2, Tanvi Govil²

¹Department of Chemistry, Biology, and Health Sciences, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA

²Karen M. Swindler Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA

Synthetic plastics are durable but difficult to decompose organically, leading to environmental accumulation. Fortunately, microorganisms present in the surrounding environment are equally diverse, and recent research has identified bacterial strains that degrade various commercial plastics to different degrees. Traditionally, identification of these strains relied on plate assays, enzyme assays, and focusing only on degrading one type of plastic per bacterium. Through this study, we assessed the growth capabilities of eight microbial strains obtained from the Rapid City Water Reclamation Facility on polypropylene (PP), polyethylene terephthalate (PET), and Polyethylene (PE). We observed that three strains showed significant degradation of PP, reducing its weight by up to 15% over four weeks. Similarly, two strains reduced PET weight by approximately 10% and PE by 12% in the same period. These results were confirmed through various plate assays and by examining substrate degradation and biofilm formation using scanning electron microscopy (SEM). To determine the purity of several bacterial strains, nanopore long reads sequencing was also conducted. The annotation conducted on the acquired genomic sequences has provided genetic knowledge about the metabolic pathways implicated in plastic depolymerization and addressed obstacles related to plastic waste utilization. This research could potentially lead to the development of microbial consortia that can effectively degrade mixed waste plastics, offering a sustainable solution to plastic pollution.

Keywords: Plastic biodegradation; Microbial strains; Biofilm formation; SEM, Nanopore Sequencing, Metabolic Pathways

South Dakota School of Mines & Technology
Dr. Rajesh Sani