Humans have produced roughly 8,300 million metric tons of plastic since the 1950s, the vast majority of which has been thrown out as waste. Only about 9% of that plastic waste has been recycled and 12% has been incinerated, leaving 79% of it to accumulate on our land and oceans, harming the environment, the food chain and, ultimately ourselves. A growing number of “bioplastics” are available on the market today, and are largely made from cellulose, a plant-based polysaccharide material. However, these materials lack the robustness and flexibility of traditional petroleum-based plastics, and require large amounts of land to grow the plants from which the polysaccharides are derived, putting additional strain on the environment and our food supply.
We are developing better alternatives to petrochemical plastics, described below.
Circe: Transforming greenhouse gases into valuable products
The Circe (Circular industries with cellular factories) Institute Project uses engineered microbes to produce polymers that can be used to manufacture a wide variety of petrochemical products with a smaller carbon footprint and minimal environmental impact than either petroleum-based plastics or plant-based bioplastics. Rather than using sugar from acres’ worth of crops as their food source, Circe’s proprietary microbes take in carbon dioxide (CO2) and hydrogen (H2) gases and produce a class of biodegradable fatty acid polymers, which can be used in a wide variety of products ranging from packaging materials to cosmetics to clothing. These polymers are non-toxic and readily degrade in the oceans and on land.
Shrilk: A degradable bioplastic derived from shrimp shells and silk protein
Shrilk is a fully degradable bioplastic made using a material called chitosan (found in shrimp shells) and a protein from silk called fibroin that mimics the microarchitecture of insects’ exoskeletons. Shrilk can be used to manufacture objects without the environmental damage caused by conventional synthetic plastics, and it rapidly biodegrades when placed in compost, releasing nitrogen-rich nutrient fertilizer. Because chitosan and fibroin are both used in FDA-approved devices, Shrilk also may be useful for creating implantable foams, films, and scaffolds for surgical closures, wound healing, tissue engineering, and regenerative medicine applications.