Feb 24, 2006
It’s not an excuse to use more plastic cups at the office water cooler, but Irish and German researchers have discovered that the soil bacterium Pseudomonas putida can eat polystyrene. This polymer, instantly recognisable in its expanded form is a key component of disposable cups, and in “plastic” plates and utensils.
Turning it into an eco-friendly plastic would significantly reduce the environmental impact of this ubiquitous, but difficult-to-recycle waste stream, according to a study scheduled to appear Kevin O’Connor of University College Dublin and colleagues there and in Germany publish details of their work in the April 1 issue of Environmental Science & Technology, but their research is no joke.
Worldwide, more than 14 million tonnes of polystyrene are produced annually, according to the US Environmental Protection Agency. Most of this ends up in landfills. Although polystyrene represents less than 1 percent of solid waste generated in the US, at least 2.3 million tons of it is dumped in US landfills annually. Just 1 percent of polystyrene waste is recycled.
The microbe is a special strain that can convert petroleum-based plastic waste, produced by pyrolysis to convert it into styrene oil, into a reusable biodegradable form. The result of microbial intervention is a biodegradable plastic known as PHA (polyhydroxyalkanoates). O’Connor suggests that a similar process might be used to convert other types of discarded plastics into PHA.
PHA is used in medicine and for plastic kitchenware, packaging film and other disposable items. It is resistant to hot liquids, greases and oils, but unlike polystyrene, it readily breaks down in soil, water, septic systems and backyard composts.