The Diversity of Fungi in Landfill and their Potential to Degrade Plastic

Plastic has been known as a recalcitrant material and is very difficult to degrade in nature, resulting in its accumulation and threatening the environment if it is not managed properly. Studies on the degradation of plastics have been obtaining much attention recently. This study aimed to determine the diversity of fungi isolated from plastic wastes in landfills and to identify the potential plastic-degrading ability of the isolates. Plastic waste samples were collected from Terjun Landfill, Medan Marelan, Indonesia. Fungi were isolated directly on potato dextrose agar medium and characterized macroscopically and microscopically. Plastic-degradation potential was screened by growing the isolates on mineral salt medium agar containing 0.5% plastic powder. Plastic sheets of low-density polyethylene and linear low-density polyethylene were used for testing the biodegradation ability of the fungi. Twenty-four different fungal morphotypes were successfully purified from plastic wastes, in which five isolates showed better growth. Molecular identification indicated that the five potential isolates belong to different species of Fusarium solani (LDPE5), Botryosphaeria laricina (LLDPE10), Aspergillus fumigatus (HDPE1), Aspergillus flavus (HDPE3) and Aspergillus niger (PP5). The biodegradation test showed that isolate LDPE5 exhibited the best activity with a 20.83% weight reduction of the plastic sheet after 45 days followed by isolate LLDPE10 with a 6.49% weight reduction. Scanning electron micrographs showed the surface of a degraded sheet of the plastic sheet became rough and wavy. Fourier transform infrared analysis showed the formation of new functional groups on the plastic sheet. Then, it indicates that fungi colonizing plastic material in landfills plays an important role in the biodegradation process.