Remarkable Bacteria Can Make Biodegradable Plastic and Even Eat Toxic Waste

Americans buy over sixty billion pounds of plastic goods a year. Even with recycling, more than one-third gets dumped and stays intact forever. But chemistry professor Sheila Browne says we can protect the environment even without changing our throwaway society.

It sounds too good to be true, but Browne is making biodegradable plastics right here, right now. "You can take a bottle made of biodegradable polymer [plastic] and stick it in a pile of leaves or mulch, and it will become water and carbon dioxide within six months," Browne says. All it needs to decompose is moisture and fungi or bacteria.

>>> Chemist Sheila Browne (far right) involves students (left to right) Pamela Maynard '97, Anastasia Dimitropoulou '97, and Tiffaney Burford '97 in her pioneering work creating biodegradable plastics.

Luckily, more than 600 types of bacteria can do the job. Bacteria actually produce the polymer, much as humans make and store fat. Normally, the bacteria use the polymer for their own energy needs. But the bacteria can be "harvested" before using the polymer they've stored, and it can be used by people. "You grow bacteria in vats, using the same fermentation process that creates beer," Browne explains. "You feed them sugar, oils, or starch, wait a few days, then harvest the polymer grown inside the bacteria." She has discovered that the nuclear magnetic resonance spectrometer can be used to determine the best harvest time and to measure how much and what kind of polymer the bacteria create.

Although Browne didn't discover polymer-making bacteria, she is one of a handful of international researchers working on a new "generation" of biodegradable polymers. In this field, she's a rarity both as a woman and as a liberal arts college professor. "Usually polymer science is taught on the graduate or postdoctoral level, so having undergraduates learn it and help with my research gives them a very special experience," Browne says. She has been invited to deliver lectures at major international conferences and published a recent article in Polymers.

"Biodegradable plastics are already widely used in Europe and Japan, because they're much more environmentally conscious," Browne says. And although these polymers are more expensive than traditional plastics, it's not price that keeps them from the American market. A law requiring companies to prove their products decompose in any environment in which they might be left "has made it virtually impossible to market biodegradable products in this country," according to Browne.

She is also pursuing other uses for polymers. Some are formed into artificial tendons; others release drugs inside the body, then disintegrate. Some bacteria can even convert oil spills and toxic waste into harmless, biodegradable polymers. Imagine the possibilities if this technology were used to its fullest extent. Sheila Browne has imagined it ... and is making it happen.