NEWS  Science  January 25, 2024  Reading time: 3 Minute(s)

Max (RS editor)

Plastic pollution has long been a global environmental challenge, with polyethylene plastic, found in everyday items like plastic bags, water bottles, and food packaging, being a major contributor. In a groundbreaking development, researchers at Rensselaer Polytechnic Institute (RPI) have unveiled a revolutionary solution that transforms polyethylene waste into a biodegradable spider silk with diverse applications in textiles, cosmetics, and medicine.

Published in Microbial Cell Factories, the study marks the first instance where scientists have utilized bacteria, specifically Pseudomonas aeruginosa, to convert polyethylene plastic into a high-value protein product resembling spider silk. Helen Zha, Ph.D., an assistant professor of chemical and biological engineering at RPI, describes this "bio-inspired spider silk" as nature's Kevlar—remarkably strong, lightweight, stretchy, tough, nontoxic, and biodegradable.

Polyethylene plastic, notorious for taking centuries to degrade naturally, poses a significant threat to the environment. The bacteria employed in the study offer a promising solution by naturally consuming polyethylene as a food source. The team at RPI successfully engineered Pseudomonas aeruginosa to convert the carbon atoms of polyethylene into a genetically encoded silk protein, achieving a yield comparable to other bacteria strains conventionally used in biomanufacturing.

The biological process at the core of this innovation draws on the age-old technique of fermentation. Mattheos Koffas, Ph.D., the Dorothy and Fred Chau '71 Career Development Constellation Professor in Biocatalysis and Metabolic Engineering, explains that the bacteria ferment the plastic, a process akin to making and preserving various foods and biochemical products. The plastic is "predigested" to facilitate bacterial consumption, mirroring how humans process food.

Collaborating with researchers at Argonne National Laboratory, the team heated and depolymerized the plastic, creating a wax-like substance. This plastic-derived wax served as the nutrient source for the bacteria culture, replacing the traditional use of sugars in fermentation. The low-energy, chemical-free process demonstrated the potential to scale up production of spider silk without harming the environment.

Helen Zha emphasizes the significance of this eco-friendly approach, stating:

"The best chemists in the world could not convert polyethylene into spider silk, but these bacteria can. We're really harnessing what nature has developed to do manufacturing for us."

While the study establishes the viability of using bacteria to convert plastic into spider silk, the researchers acknowledge the need for further efficiency improvements.

Dean Shekhar Garde commends Professors Zha and Koffas for pioneering a novel approach that merges biological engineering with materials science. Their work represents a promising step toward protecting the environment and reducing dependence on nonrenewable resources.

As the research progresses, the prospect of commercially available, upcycled spider silk products brings hope for a sustainable future, where innovative solutions contribute to the global fight against plastic pollution.

 IMAGES CREDITS: RENSSELAER POLYTECHNIC INSTITUTE