Biodegradation of low-density polyethylene films commercially labeled as biodegradable pretreated with UV-B radiation by Pleurotus ostreatus grown in liquid fermentation

Abstract

Biodegradable plastics are eco-friendly materials that can be safely incorporated into the environment to reduce plastic pollution. In this work, Pleurotus ostreatus was grown in unirradiated (UnBPE) and UV-B irradiated low-density polyethylene films (IrBPE) commercially labeled as biodegradable for four weeks in liquid fermentation. Fungal growth, laccase (Lac), lignin peroxidase (LiP), unspecific peroxygenase (UnP), and manganese peroxidase (MnP) activities, and contact angle, as well as changes in the surface morphology and chemical structure of the samples using SEM and FTIR spectroscopy, respectively, were evaluated. Production of fungal biomass was similar in both IrBPE and UnBPE samples. P. ostreatus showed higher enzyme activities in IrBPE than in UnBPE. From all the enzymes tested, Lac had the highest activity (5836.69 U/L) followed by LiP (2789.15 U/L), UnP (2681.04 U/L), and MnP (983.37 U/L) in IrBPE. The lowest contact angle was observed at week four, decreasing from 67.33° to 50.66° for IrBPE. The FTIR surface spectra of the samples showed an increase in distinctive oxidation bands in the polymer chain, corresponding to functional groups such as carbonyls, vinyls, and hydroxyls. IrBPE showed fractures on its surface. Low-density polyethylene commercially labeled as biodegradable enhanced its biodegradation when exposed to pretreatment with UV-B
radiation.