Phenolic-resin-eating superworms as a platform for discovering microorganisms that degrade phenolic thermosets

초록

Electronic waste (e-waste) is associated with escalating problems that necessitate innovative solutions for managing phenolic resins, which are prevalent components of discarded printed circuit boards (PCBs). Here, we report that superworms (Zophobas atratus) which naturally ingest polyphenolic materials, provide a biological platform for identifying microorganisms capable of degrading phenolic resins. Most microbial biodegradation systems primarily focus on thermoplastics, but here we directly demonstrate molecular-weight changes and measurable thermoset-resin degradation. Floral foam was selected as a model for phenolic resins due to its porous structure and high surface area, which facilitate bacterial and enzymatic degradation in superworm guts. Superworms exclusively fed floral foam demonstrated survival rates comparable to those fed bran for 28 d. Structural changes indicative of oxidative biodegradation of the phenolic resin were revealed, with stable carbon isotope analysis suggesting that the floral foam had been assimilated into superworm tissue. Significant microbial-community changes were observed during gut microbiome analysis, with notably higher levels of Citrobacter, Cronobacter, and Enterococcus genera, which are known for their abilities to biodegrade plastic, recorded for the floral-foam-fed group. This study provides a biological approach for degrading thermosetting plastics and screening potential microorganisms for future applications in eco-friendly phenolic-resin-based thermoset e-waste management.

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