Everyday plastic products produce microplastics fragments. They are tiny, nearly indestructible, as we learn more about microplastics, the news keeps getting worse.
Since few decades we know that microplastics are in our oceans and soil. We’re now discovering them in the unlikeliest of places: our arteries, lungs and even placentas. Microplastics can take anywhere from 100 to 1000 years to break down and, in the meantime, our planet and bodies are becoming more polluted with these materials every day.
The chemical nature of widely used petroleum-based plastic polymers makes them inaccessible to biological processing, leading to an accumulation of microplastics in the natural environment. One way to mitigate this crisis is adoption of plastics that biodegrade if released into natural environments.
New research from scientists at the University of California San Diego and materials-science company Algenesis appeared in Nature Scientific Reports demonstrate the opportunity to produce bio-plastics accessible to a biological degradation process.
Their plant-based polymers biodegrade — even at the microplastic level — in under seven months.
They generated microplastic particles from a bio-based, biodegradable thermoplastic polyurethane (TPU-FC1) and demonstrated their rapid biodegradation via direct visualization and respirometry. The idea is that microplastics generated from environmentally biodegradable polyester polyurethanes might rapidly degrade in the environment and hence not persist in the natural environment.
The results indicated that TPU-FC1 particles completely degraded within 200 days, while similar particles derived from a non-biodegradable polymer, ethyl vinyl acetate, showed no reduction of particle number in the same time frame. Tracking CO2 production via respirometry under identical composting conditions further confirmed biodegradation and mineralization of TPU-FC1 particles.
The research also identifies organisms responsible for this biodegradation. A bacterial strain belonging to the genus Rhodococcus was isolated that grows rapidly on TPU-FC1 alone. Feeding studies using this Rhodococcus strain indicated that it can depolymerize the TPU-FC1 material into the starting monomers, which can be quickly consumed by the Rhodococcus and other microorganisms.
Given the conclusion that the bio-based TPU-FC1 is fully biodegradable, scientists explored possible product applications for this material.
Creating an eco-friendly alternative to petroleum-based plastics is only the start of the long road to viability. The next challenge is to be able to use the new material on pre-existing manufacturing equipment that was originally built for traditional plastic.
References:
Rapid biodegradation of microplastics generated from bio‑based thermoplastic polyurethane – Marco N. Allemann, Marissa Tessman, Jaysen Reindel, Gordon B. Scofield, Payton Evans, Robert S. Pomeroy, Michael D. Burkart, Stephen P. Mayfield & Ryan Simkovsky; Nature, Scientific Reports; (2024) 14:6036.
