Govind Makaram

Polyethylene (PE) is one of the most ubiquitous plastics used in our society. However, PE resistance to degradation by abiotic factors has resulted in a large influx of plastic waste entering natural ecosystems. As a result, some microbial communities have developed mechanisms to degrade polyethylene. Studying these communities is crucial to better understand mechanisms to remediate plastic pollution.
This project focused on understanding the microbial communities able to degrade PE. As a result, the project was divided into three main areas: isolation of specific genera within existing cultures, maintenance and growth of existing cultures, and further acquisition of new cultures through environmental isolation. Genomic information had already been obtained from existing cultures sent to the UMN Genomic Center for sequencing and species identification. This information was used to isolate specific genera from the mixed culture. Existing microbial cultures were maintained using a combination of a plastic-containing media and a salt solution. The media given transitioned from low chain-length polyethylene to longer chain-length polyethylene as a method to enrich the culture for strains reliant on polyethylene-like compounds for metabolism. To quantify growth, both optical density and hydrocarbon content were used. The hydrocarbon content (i.e. non-metabolized plastic in solution) was measured using Gas Chromatography (GC). To acquire future samples, a polyethylene sampler was placed in several lakes around the Twin Cities area in October with the hope that a microbial community could be isolated by the Spring. Lakes were chosen as it was believed that an environment saturated with motorboat oil (i.e. long hydrocarbons) contained microbes capable of degrading polyethylene.