Using Bacteria to Break Down Plastic Waste

Twelfth grade scientists combat phthalate pollution at the local level.

Miranda Wang and Jeanny Yao present an inspirational new method to break down plastic waste.

Their targeted contaminants are phthalates, classified by the EPA as a top priority pollutant. Every year at least 470 million pounds of phthalates contaminate our air, soil and water.

Phthalates are used in plastic because they increase flexibility, durability and transparency. When acting as a hormone disruptor phthalates can cause cancer and birth defects.  

Phthalates are part of the plastic but not covalently bonded to the plastic’s chemical backbone and can escape into the environment. Baby toys, beverage containers, cosmetics and food wraps all contain phthalates. The contamination can be absorbed by skin contact, ingested and inhaled.

The birth of the idea came from a class trip to the Vancouver Waste Transfer Station. Wang and Yao saw mountains of plastic waste. They began to do research and better understand the downside of the convenience of plastics.

Ecosystems can be destroyed, natural resources can be polluted and available land space is reduced. Scaling back on the production of plastics is a hard sell, and does not address the plastic waste already produced. Of particular interest to Miranda and Jeanny was the North Pacific Gyre.

The students drafted a proposal and obtained research help from the University of British Columbia. They collected soil samples from three different sites, including a bird sanctuary and a landfill. Some bacteria were found to have a growth rate inverse from the growth rate of phthalates. Because of this Wang and Yao concluded that the bacteria were feeding off of the pollutant.

Next the students isolated the specific bacteria eating the phthalates through gene amplification sequencing. Of the several bacteria found two strains were not previously known to actively degrade phthalates, resulting in a completely new discovery.

The bacteria found can transform phthalates into carbon dioxide, water and alcohol. The most efficient degraders came from the landfill site.

Jeanny and Miranda recognize that they are not the first scientists to use bacteria to break down pollutants. However, they are proud to be the first to use local bacteria to deal with a local problem.

The research was presented at the Sanofi BioGENEius Challenge competition and recognized with the greatest commercial potential.

Jeanny says that the long term goal is to create model organisms that will break down phthalates and other contaminants, eventually moving on to solid plastic waste.