Investigations

of PETase from Ideonella sakaiensis, a plastic-degrading bacterium

Noah Wallace

Faculty Sponsor: Dr. Todd Gruber,

Department

of Molecular Biology and Chemistry

Abstract

PETase is an enzyme that is capable of degrading polyethylene terephthalate, the plastic commonly found in plastic water bottles. We have developed assays to measure rates of plastic degradation by this enzyme and have cloned the PETase enzyme into an expression plasmid under an inducible promoter for use in E. coli bacteria. We have expressed the enzyme and can detect activity via a colorimetric assay using p-nitrophenyl acetate (PNPA), a small molecule substrate analog. This assay is straightforward and useful. We have additionally investigated the growth of Ideonella sakaiensis, the bacterium from which PETase was cloned, on different sources of PET. Further, we have developed an assay in which plastic degradation can be monitored spectroscopically, opening the possibility of selecting for improved mutants of the parent organism.

Finally, we have determined that Ideonella likely forms a biofilm on the PET plastic in order to begin its degradation process.

Other strains of bacteria have been found that can deteriorate other types of plastic and it is believed that there are many other forms of bacteria that have evolved the ability to metabolize plastic as a carbon source. We believe an important next step in our research path is developing methodology to screen for other forms of plastic degrading bacteria. Current methodologies are sparse and take on average several months, but we believe with our assays we can develop a methodology that cuts this screening time significantly. Further environmental screening needs to be done to find these bacteria to better understand the enzymes that are used in this process.

Noah Wallace is a member of the class of 2020 at Christopher Newport University. He majored in Biochemistry with minors in Business administration in the Biotechnology and Management Program, Leadership Studies in the President’s Leadership Program, and is a member of the Honors Program. Outside of his studies he has completed over 1000 hours of undergraduate research both during the school year and as a Summer Scholar for two summers. He is a brother of Kappa Delta Rho where he is serving as the Executive Vice President as well as a brother of the National Chemistry Fraternity, Alpha Chi Sigma. Noah is staying at CNU for an additional year to pursue a Master’s Degree in Environmental Science with a thesis topic focused on plastic degrading bacteria.