Degradation of polyethylene by a fungus, Penicillium simplicissimum YK

Abstract

We isolated a strain of Penicillium simplicissimum, YK, for use in the biodegradation of polyethylene, characterizing the fungus and examining how to treat the polyethylene before cultivation to make degradation more complete. Degradation was monitored by high-temperature gel-permeation chromatography of the molecular weight distribution of polyethylene before and after the fungus was cultivated with it. Polyethylene with starting molecular weights of 4000 to 28,000 had lower molecular weights after 3 months of liquid cultivation with hyphae of the fungus. UV irradiation of polyethylene or its incubation with nitric acid at 80°C for 6 days before cultivation caused functional groups to be inserted into the polyethylene. The strain grew better on a solid medium with 0.5% polyethylene when it was irradiated for 500 h than when it was not irradiated. Polyethylene with a molecular weight of 100,000 or higher after nitric acid treatment had lower molecular weight after 3 months of liquid cultivation with hyphae of the fungus. The efficiency of polyethylene degradation depended on the growth phase in pure cultivation of the fungus. Functional groups inserted into polyethylene aided biodegradation. Bioremediation of polyethylene may become possible.