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Biodegradation of pre-treated low-density polyethylene (LDPE) by Yarrowia lipolytica determined by oxidation and molecular weight reduction
Summary
Researchers pre-treated low-density polyethylene with physicochemical methods before exposing it to the yeast Yarrowia lipolytica, finding that pre-treatment reduced molecular weight by roughly 9% and enabled effective microbial attachment, though biological degradation alone achieved only modest further breakdown.
• Proposed physicochemical and biological treatments enhance LDPE biodegradability. • GPC analysis shows ∼9% molecular weight reduction after physicochemical treatments. • GPC analysis shows ∼1% molecular weight reduction after microbial exposure. • Yarrowia lipolytica effectively attaches to and degrades pre-treated LDPE. • Results suggest Y. lipolytica could biodegrade pre-treated LDPE in about 12 years. Millions of metric tonnes of plastic waste are generated every year, with a minimal portion being recycled. Therefore, there is an urgent need to find effective and sustainable methods for plastic degradation, especially polyethylene, the most manufactured polymer globally. Here, we emulate the strategies documented for beetles, characterized by a combination of physical, chemical, and microbiological treatments, to biodegrade low-density polyethylene (LDPE). Importantly, we characterize LDPE degradation through multiple techniques, including weight loss analysis, FTIR, GPC, GC–MS, and SEM, which allowed us to identify the optimal combination of treatments to enhance LDPE biodegradation. Contrary to some expectations, we find that ultrasonication does not contribute to LDPE degradation but may instead protect against its fragmentation. However, we successfully introduce carbonyl groups into the polymer backbone, by simply exposing LDPE to environmentally friendly anionic surfactant. This pretreatment effectively cleaves LDPE by approximately 9%, breaking it into shorter carbon chains that are more accessible to microbes for subsequent biodegradation. The yeast Yarrowia lipolytica , isolated from fuel tanks and able to grow in n -paraffines, not only outperforms other microbes in assays of short carbon chain degradation, but also attaches to the LDPE surface, where it survives and grows using LDPE as sole carbon source. Our findings, therefore, pave the way for further developing a potential solution to plastic waste, calling for interdisciplinary research and innovative solutions in tackling global environmental challenges.