Using DNS to Design a High-Throughput Assay for Plastic-Degrading Enzymes

• Mekhi Williams, Chemical Engineering, University of Delaware

• Mark Blenner, Chemical and Biomolecular Engineering, University of Delaware

The current methods for plastic recycling are insufficient to combat the current rate of plastic waste being produced, so novel ways to solve this issue are in high demand. Our group has been conducting research on plastic-degrading enzymes native to the gut microbiomes of mealworms to develop a more efficient process for recycling plastic. This research involves dosing low-density polyethylene (LDPE) films with these enzymes and then screening the plastic on a Fourier-transform infrared spectrometer (FTIR) to detect any chemical changes on the film. Use of the FTIR is time-consuming and can take hours to analyze if multiple experiments are being conducted. We would be able to operate more efficiently if there was a more high-throughput method of determining if an enzyme chemically altered the plastic, which may be achievable through the use of 3-5 dinitrosalicylic acid (DNS). DNS is a reagent that is used in the detection of reducing sugars. It reacts with the carbonyl bond on the sugar, which causes a color change that is readable on a spectrophotometer. We hypothesized that DNS could be used similarly to detect chemical changes in the plastic because FTIR analysis showed that our plastic-degrading enzymes added carbonyl bonds to the films. An experimental procedure was then created to use DNS to detect enzyme activity on the plastic films. The films were dosed with an enzyme known to add carbonyl groups to the plastic. The films were then washed and dosed with the DNS reagent. This procedure was repeated and altered for optimization purposes, but the overall results of these screenings suggest that it will be a useful and efficient method to conduct enzyme assays in the future.