Enzyme-Loaded Biodegradable Plastics Dissolve in the Deep Ocean Within Months
University of Tokyo researchers have embedded heat-stable enzymes inside compostable plastics that cause them to lose nearly all their mass within five months, even at depths of 5,500 metres.
A team led by researchers at the University of Tokyo has engineered compostable plastics that carry their own built-in decomposition mechanism: freeze-dried, heat-stable enzymes embedded directly into the plastic matrix. The scientists tested four polymers — PBS, PBSA, PCL, and PBAT — shaped into both films and microbeads to mimic real marine waste. Two enzymes were used: Candida antarctica lipase B and Humicola insolens cutinase, both able to survive the high temperatures needed to melt and mould plastics without losing their protein structure. In laboratory tests at 757 metres depth, three polymer types with just 3 % cutinase content lost nearly all their mass within five months, whereas enzyme-free control samples barely changed. The fourth polymer, PBAT, shed just over 12 % under the same conditions. Crucially, the enzymes remained functional at 5,503 metres — among the deepest ocean environments — and in shallow coastal water, just 0.1 % enzyme concentration was enough to significantly accelerate breakdown. The researchers caution that improved marine biodegradability does not by itself guarantee environmental sustainability, but the work opens a pathway to single-use plastics that self-digest wherever they end up in the ocean. The results were published in October 2026 and could feed into international negotiations on a global plastics treaty.
