Chinese Scientists Develop Self-Degrading Plastic Material

Chinese scientists have created a plastic material containing living bacteria that can be triggered to break down completely without leaving microplastics. The material uses two strains of the common bacterium Bacillus subtilis that work together to degrade polycaprolactone, a polymer used in 3D printing and some medical sutures.

The bacteria remain dormant as spores until placed in a nutrient broth and heated to 50 degrees Celsius. Once activated, the strains produce different enzymes that degrade the plastic. One enzyme cuts long polymer chains at random points while the other breaks the resulting fragments down from the ends into their smallest molecular building blocks.

The process completely degrades the material within six days. The study, published in the journal ACS Applied Polymer Materials, states that the cooperative enzymatic activity within the microbial consortia outperforms that of a single-strain system.

Previous efforts to create living plastics relied on a single enzyme. The Chinese researchers engineered two Bacillus subtilis strains, each producing a different polymer-degrading enzyme, to improve efficiency. The microbes were incorporated into the plastic in spore form to protect them until degradation was required.

The resulting material maintains stable mechanical properties suitable for its intended uses. Scientists protected the bacteria in their dormant spore form during the manufacturing process.

Researchers plan to develop a trigger mechanism that activates the bacterial spores in water, where much plastic waste accumulates. They also intend to adapt the approach for other common plastics, including those used in single-use products. Current conventional plastics are designed for single use but can persist in the environment for years.

The new material addresses the challenge of non-biodegradable waste by enabling on-command degradation down to base building blocks.