Degradation of polymers by fungi isolated from dumpsites

Abstract

The present study aims at identifying the ability of nine fungal species, which were isolated from garbage of different sites to degrade commonly used polymers, viz. polyethylene, polystyrene, and polyurethane when treated with four methods separately, viz., sterilized and unsterilized drench methods, sterilized and unsterilized mulching methods for four months. All the species considerably degraded the polymers by the above-mentioned methods. However, polystyrene demonstrated the greatest degradation compared to the other two polymers, particularly by sterilized and unsterilized drench methods. Seven fungal species caused greater than 50% weight loss of polystyrene when treated with the above-mentioned methods. Aspergillus flavus instigated the greatest weight loss (74.78 ± 2.85%) by the unsterilized drench method. Of nine, three species caused more than 50% weight loss of polyurethane by the unsterilized drench method. A. niger divulged greater than 50% weight loss of the polymer by sterilized drench method. In this study, polyethylene was found least degraded compared to polystyrene and polyurethane by the selected fungal species. Of nine, only two species, viz. Aspergillus flavus and A. niger caused a higher than 50% weight loss of polyethylene only by sterilized drench method. Scanning Electron Microscopy (SEM) images of six elevated degraded polymer samples were taken to reveal the formation of spores and hyphae on the surface of the plastic. The images demonstrated the formation of cracks and crevices on the surface of different polymers by spores and the fungal hyphae.