What will isolating bacteria that munch on polyethylene (PE) get you? For sixteen-year-old Daniel Burd, the top prize at this year’s Canada-Wide Science Fair. As his hometown paper The Waterloo Region Record reports, Burd discovered two strains of bacteria that work in tandem to break down plastic bags rapidly—in his experiments, 43% of the way within six weeks.
Since PE can take up to an estimated 1,000 years to decompose, the world’s reliance on it has been raised as an environmental crisis. Plastic bags are filling up landfills for the long haul and, more problematically, finding their way to water where their indigestible fragments kill ocean life. The most notable aqua-accumulation is a plastic mass between Hawaii and Los Angeles reported by one research team to be nearly twice the size of Texas and growing tenfold every two or three years.
Burd says the abundance of plastic bags in his own home led him to investigate what others were doing with them. Apparently, he wasn’t satisfied. His project’s premise was that if the bags do break down in nature eventually, a microorganism (or group of them) was responsible and could be concentrated for greater effect. To find the decomposer, Burd added ground-up PE to a microbial breeding ground of household chemicals, yeast and water. After systematically weeding out the unproductive bacteria strains, Sphingomonas and Pseudomonas were left.
According to Burd, industrial application would only require a fermenter, a growth medium, the bacteria and the plastic. Since heat is generated in the process, maintaining the ideal temperate for decomposition would not be too energy-intensive.
So what are the drawbacks? Burd says each microbe during the process releases 0.01% of its own weight in carbon dioxide. For a large-scale decomposition operation, the impact of those emissions might have to be considered. Also, it could be argued that, at least in many cases, it would be more responsible simply to recycle the PE—conserving the carbon already invested in it—than to break it down. Nevertheless, this teenager’s achievement could pave the way for some exciting new strategies in managing our PE.