When exposed to heat and water, the enzymes free themselves from the surrounding polymer chains and begin munching away on PLA molecules. The enzymes turn the PLA into lactic acid, which is consumed by various microbes in the soil.
Other plastic degradation processes yield tiny plastic particles called microplastics. In recent years, surveys have found microplastic pollution in the organs of humans and animals, as well in some of the planet’s most remote ecosystems.
The new composting method turns 98 percent of the PLA into simple molecules.