Degradation of polyethylene particles by Trichoderma harzianum and recombinant laccase cloned from the strain

Abstract

Polyethylene (PE) is a convenient and inexpensive polymer that is widely used in daily life. However, PE products are recalcitrant to degradation in the environment, leading to increasing plastic pollution. This has inspired the search for effective microorganisms and enzymes that can biodegrade PE. In this study, a fungal strain that degrades PE was isolated from soil contaminated with plastic and identified as Trichoderma harzianum. The strain was cultured with PE as the sole carbon source for 30 days, and the weight loss of PE particles was 3.39 ± 0.3%. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectra showed holes and oxygenated functional groups on the surface of the degraded PE particles. Gas chromatography–mass spectrometry (GC–MS) detected products with different carbon atom numbers. In addition, a potential PE degrading enzyme was screened from T. harzianum and identified as laccase. After PE was incubated with the recombinant laccase for 96 h, SEM, FTIR, and GC–MS showed the degradation of PE particles. The results showed that T. harzianum had the ability to degrade PE, which probably was attributed to the laccase produced by this strain. This study contributes promising tools for the degradation of PE enzyme.