Enzymatic Acceleration of PHA-Based Microplastic Degradation by Protease, Cellulase, and Amylase with Lactobacillus plan

Overview

This project investigated how the different enzymes Amylase, Cellulase, and Protease affect the degradation of biodegradable microplastics using Lactobacillus plantarum set at pH6. It has been discovered that probiotic bacteria Lactobacillus plantarum, which is widely regarded as harmless to humans, can degrade biodegradable microplastics under laboratory conditions (Kim, 2024). The experiment did reveal modest degradation under certain conditions, especially more acidic pH6, but overall the rate of breakdown was very slow. Even at the optimal pH level discovered by the experiment, the microplastics only degraded 3.77% of the initial amount which means it would take 260 days to fully degrade. Given the steady increase of plastic waste into the environment, a slow degradation process is unlikely to be practical for real-world application. So, the project goal was to investigate 1) if adding enzyme solutions to the harmless bacteria L. Plantarum will speed up the process of degradation, and 2) How different enzymes (Protease, Cellulase, Amylase) affect the rate of degradation of PHA-based biodegradable microplastics using L. Plantarum. In the experiment, biodegradable microplastics were placed in agar set at pH6 with the three different enzymes each containing Lactobacillus plantarum. There were 10 trials for each enzyme and over 6 days, changes in the total area of the microplastics were recorded by taking pictures daily to assess degradation. Data was analyzed using color recognition with ImageJ, an advanced image analysis tool to measure the change in total area of the microplastics. The qualitative analysis shows color change as well visible degradation of the particles with the naked eye. The ImageJ analysis results showed that microplastics degraded more effectively when exposed to Amylase than when exposed to other enzymes (16.11% for 6 days). Based on the results, it is predicted that for Amylase it would take around 36 days, Protease would take 43 days, and Cellulase would take around 46 days to fully degrade the microplastics (Without enzymes it would take 138 days (Control)). The findings of this investigation could be applied to areas with large amounts of microplastic and pollutants buildup like wetlands and estuaries as a modular in‑stream device that captures and treats microplastics then releases cleaner water back out. Another potential application is a micro-scale device to help degrade and remove microplastics inside the body. While still theoretical, this idea could potentially address microplastic pollution both environmentally and medically. The experiment could be improved by enhancing biodegradable plastic degradation through optimizing enzyme performance, testing a range of pH levels, exploring different types of bacteria, varying incubation environments such as temperature, and considering the size of microplastic particles. These findings could have significant implications for promoting more sustainable and safe approaches to plastic removal and reducing plastic pollution.

Competition history

• CSEF 2026 Earth & Environmental Sciences(Senior Division) · Entry S-08-22

Related projects

Closest projects by meaning, across every fair and year in the corpus.

Browse more like this

• All Earth and Environmental Sciences projects
• CSEF Earth and Environmental Sciences projects
• Every CSEF 2026 project