In the midst of an international waste crisis, could a common starch-eating fungus help save us?

Overview

Starch derived from plant biomass is used to make consumer products that can be composted. Unfortunately, the time it takes to complete composting (90 days) means that many of these materials end up in landfills. These artificial environments do not allow for further decomposition making these products environmentally damaging. I selected A. oryzae for this project because it is a food-grade fungi that could potentially have the depolymerization ability to break up PHAs while composting. I put three samples of plant starch plastic-based cups each in two bins, one control with only compost and one experimental with an added sample of 20 grams of Aspergillus oryzae spores and allowed them to compost for 6 weeks. The bins were put in a room-temperature area and were mixed and watered twice a week. The mean change in mass of the control group was 2.4 grams and the mean of the experimental group was 5.1 grams, showing a large difference in mass change and rate of decomposition between the groups. There was a 95% confidence interval and a two-tailed p-value of 0.0258 derived from a t-value of 3.4587 and four degrees of freedom. Cups composted with added fungi lost an average of 5.07 g compared to cups composted without added fungi (2.4 g, t = 3.46, 1 df, P = 0.026). These results are consistent with the hypothesis that adding A. oryzae spores will increase the efficiency of composting for commercial products constructed from plant-based starch. Therefore, I accept the hypothesis stating a quicker rate of decomposition of plant starch products with Aspergillus oryzae. This study finds it statistically highly probable that Aspergillus oryzae accelerates the decomposition of plant starch-based alternative plastics.