Teen uses microbes to biodegrade plastic bags

Polyethylene bags are an environmental curse because they are expected to take thousands of years to decompose, and worldwide their use is growing.

In India, for example, over the last 15 years plastic bags have taken over from traditional, biodegradable or recyclable wrappings and when I visited there recently I was appalled by how much the urban landscape was spoiled by discarded bags caught in fences, railings, hedges, trees or just lying on the ground.

The Record recently reported that Canadian high school student Daniel Burd from in Warterloo, Ontario, developed a process for breaking down plastic bags and demonstrated it at a school science fair.

Burd reasoned that slow as the process was, something must make the plastic degrade, and that something would probably be a soil living microbe (bacteria, amoeba, or yeast).

He experimented by taking some dirt from a rubbish dump and adding that to a mixture of ground up plastic bags and a bacterial growth medium he made from yeast and simple household chemicals. After a while he discovered a noticeable decomposition in his bags and he extracted the bacteria that were thriving on the plastic.

Eventually he identified two strains, Sphingomonas and Pseudomonas, that when both present and in ideal conditions would reduce the plastic mass by 32%. He then developed a digester that would give the bacteria their ideal environment and achieved a 43% degradation of the ground bags in six weeks.

Burd thinks this would be easy to scale up to industrial scale as all that's needed is a fermenter, growth medium and waste plastic. The bacteria provide most of the energy required by producing heat as they eat. The only waste is water and a carbon dioxide.

Burd won first prize in a Canada wide science fair taking home $10,000 in prize money, a $20,000 scholarship and recognition for his use of science to help the environment.


Bruce Clement is a keen domain name investor and commentator. You are free to copy this article under the http://creativecommons.org/licenses/by-nd/3.0/ licence as long as you publish it unchanged and link either to Bruce's blog ┬┐Que? at http://www.que.co.nz// or to his hub site at http://www.clement.co.nz/

Tags: environment