In a new study, a research team has developed a revolutionary enzyme, PET2-21M. This new catalytic enzyme significantly enhances the biodegradation of PET plastics to produce dramatically more effective recycling of bottle-grade materials. This new enzyme—a cutinase from a leaf-degrading fungus—shows incredible efficiency at moderate temperatures, offering a significant leap forward for industrial-scale enzymatic recycling. The team’s findings might pave the way for fewer catalytic requirements and thus lower catalytic costs for the recycling industry.
PET2-21M not only surpasses the success of its predecessor, but demonstrates conversion rates that far exceed the previous enzyme at reduced dosages. At the suggested PET2-21M dosage of 5 mg L-1, PET2-21M achieved a notable 44% PET conversion. By comparison, the former used enzyme LCC-ICCG only achieved a 29% conversion. Under the conditions of 60 °C at enzyme dosage of 10 mg L^-1, PET2-21M showed a conversion rate of 79% after 48 h. This finding is almost comparable to LCC-ICCG, which achieved a maximum conversion of 95% with a higher optimal temperature.
Enhancing Biodegradation Efficiency
The advanced enzyme PET2-21M has made the biodegradation process for bottle-grade PET powders incredibly efficient. In these controlled experimental systems, it degraded over 95% of commercially available powdered PET in only 24 hours at 60 °C. This extraordinary speed underscores its formidable potential to address plastics that have formed vexing environmental scourges for decades. This rapid degradation is a key feature that could help enhance recycling processes, tackling the growing global crisis of plastic waste.
TACE1-26YM has slightly lower efficiency than PET2-21M, despite increased substrate loading. Especially efficient at concentrations of up to 40 g L-1. This high versatility allows this process to be used widely across industrial applications that have higher concentrations of PET available. Even when halved to an enzyme concentration of 2.5 mg L-1, PET2-21M maintained around 50% degradation efficiency, underscoring its robustness and potential for cost-effective implementation in recycling facilities.
Comparison with Previous Enzymes
Further expanding upon the successes of its predecessor, PET2-14M, the development of PET2-21M was initiated. The original variant demonstrated a remarkable improvement in catalytic activity compared to the wild-type native enzyme. Early assays demonstrated that it reached a total product yield almost 28.6 times greater than the original. Another variant, PET2-14M-6Hot, reached notable yields of up to 691 mg L-1 in only 137 hours of culture. This points to remarkable developments in enzymatic efficiency.
PET2-14M-6Hot showed outstanding catalytic activity on PET/cotton blends, producing 62.8 mM of products. LCC-ICCG provided a much lower yield of only 46.7 mM under similar conditions. As impressive as their new enzymes were on pure PET, they performed at least as well on compositions of different mixed materials. This opens them up to more uses further down the recycling stream.
Large-Scale Production and Future Implications
As a result, the research team has most efficiently accomplished large-scale production of both PET2-14M-6Hot and PET2-21M in the yeast host Komagataella phaffii. Regardless, this breakthrough represents a big leap forward in the practical application of these enzymes. This biotechnological breakthrough enables high-productivity production processes that can match the industrial requirements, clearing the path for commercial adoption.