The involvement of wood decay fungi and the importance of their enzymes in polyethylene degradation is well documented. Therefore, decay-resistant hardwood associated fungi should be better degraders with their versatile enzymatic systems. In the current study, decaying hardwood associated fungi were isolated and their ability to degrade low-density polyethylene (LDPE) was assessed. Thirty-three isolates were identified by sequencing the internal transcribed spacer region of nuclear ribosomal DNA. Randomly selected isolates were tested for laccase producing abilities. Three species were selected to test their potentials in LDPE sheet degradation. Fungi were incubated in Czapek-Dox broth containing 20-micron LDPE sheets at room temperature for 60 days. The biodegradation signatures were assessed by analyzing the changes in structural characteristics of LDPE using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), percent reduction of tensile properties, and weight loss. FTIR analysis revealed changes in certain functional groups compared with the control, indicating chemical changes resulting from the treatment. LDPE sheets incubated with fungi showed cracks and holes under SEM analysis, percent reduction in tensile properties, and weight loss, which are the signatures of degradation. This study revealed that the hardwood decaying basidiomycetes, Phlebiopsis flavidoalba, Schizophyllum commune, and Phanerodontia chrysosporium have the potential for in vitro LDPE degradation.

The involvement of microorganisms in low-density polyethylene (LDPE) degradation is widely studied across the globe. Even though soil, landfills, and garbage dumps are reported to be promising niches for such organisms, recently the involvement of wood decay fungi in polyethylene degradation is highlighted. In light of this, 50 fungal samples isolated from decaying hardwoods were assessed for their wood degradation ability and for their depolymerization enzymatic activities. For the LDPE deterioration assay, 22 fungal isolates having wood decay ability and de-polymerization enzymatic activities were selected. Fungal cultures with LDPE sheets (2 cm x 10 cm x 37.5 μm) were incubated in the presence and in the absence of wood as the carbon source (C) for 45 days. Degradation was measured by weight loss, changes in tensile properties, reduction in contact angle, changes of functional groups in Fourier-transform infrared spectroscopy, Scanning electron microscopic imaging, and CO2 evolution by strum test. Among the isolates incubated in the absence of wood, Phlebiopsis flavidoalba out-performed the other fungal species showing the highest percentage of weight reduction (23.68 ± 0.34%), and the lowest contact angle (64.28° ± 5.01). Biodegradation of LDPE by P. flavidoalba was further supported by 46.79 ± 0.67% of the mass loss, and 3.07 ± 0.13% of CO2 emission (mg/L) in the strum test. The most striking feature of the experiment was that all the isolates showed elevated degradation of LDPE in the absence of wood than that in the presence of wood. It is clear that in the absence of a preferred C source, wood decay fungi thrive to utilize any available C source (LDPE in this case) showing the metabolic adaptability of fungi to survive under stressful conditions. A potential mechanism for LDPE degradation is also proposed.