PS foam converts to Biodegradable plastic thanks to microbes

10-Mar-06

Bacteria could to significantly reduce the environmental impact of polystyrene- the omnipresent, but difficult-to-recycle. The microbes, a special strain of the soil bacterium Pseudomonas putida, convert polystyrene foam into a biodegradable plastic. The study utilized pyrolysis, a process that transforms materials by heating them in the absence of oxygen, to convert polystyrene into styrene oil. The researchers then supplied this oil to P. putida, a bacterium that can feed on styrene, which converted the oil into a biodegradable plastic known as PHA (polyhydroxyalkanoates). The process might also be used to convert other types of discarded plastics into PHA. PHA has application in medicines and can be used to make plastic kitchenware, packaging film and other disposable items. The biodegradable plastic is resistant to hot liquids, greases and oils, and can have a long shelf life. But unlike polystyrene, it readily breaks down in soil, water, septic systems and backyard composts. Over 14 million metric tons of polystyrene is produced annually worldwide, most of which ends up in landfills. Although polystyrene represents less than 1% of solid waste generated in the United States, at least 2.3 million tons of it is dumped in U.S. landfills each year. Only 1% of polystyrene waste is currently recycled.