PJB-2021-658
ISOLATION AND CHARACTERIZATION OF PLASTIC DEGRADING FUNGI FROM THE DUMPING SITES
JUNAID AZEEM
Abstract
The emerging plastic waste particularly poly-ethylene, the most common type of plastic poses an imminent threat to the ecosystem and health. These are used in daily life and being increasing immensely, the favorable properties such as durability and strength are now becoming a burden. These properties make them more persistent in the environment. Saprophytic fungi belong to a very diverse group of microorganisms that are mainly decomposers and act as natural degraders. Present study focused on the isolation and screening of potential fungi capable of degrading low-density polyethylene. For that purpose, plastic dumping sites were selected for the isolation and about thirty fungal isolates were isolated. Among them, ten were selected based on maximum growth on plastic on M1 screening media. While, two of them gave maximum growth on plastic screening media and were selected as SJ3 and Burn_2, later identified using 18S rRNA as Aspergillus tubingensis SJ3, Fusarium equiseti Burn_2. Both gave the highest results of plastic degradation in terms of agar plate assay and weight reduction analysis. In the agar plate assay, results showed that Aspergillus tubingensis SJ3 gave the most dominant growth pattern using plastic pieces of polyethylene as the sole source of carbon. In addition, results of weight reduction indicated that Aspergillus tubingensis SJ3 gave results of 41% reduction, while, Fusarium equiseti Burn_2 showed 21% of weight reduction of plastic pieces. In CO2 evolution test, results showed that Aspergillus tubingensis SJ3 and Fusarium equiseti Burn_2 had the highest values of 2.70 gL-1 and 2.62 gL-1 against control 2.00 gL-1. In the case of FTIR, main bands were shown in the region of 2900 cm-1 with sharp peaks, while, minor peaks were shown in 1500-1400 cm-1 indicated that CH2 and C-C bonds were affected by fungal isolates. The plastic pieces treated with Fusarium equiseti Burn-2-in and Aspergillus tubingensis SJ3 indicated cracks, surface erosion as compared to the untreated plastic piece with a clear and smooth surface in SEM analysis. These results evidently indicated that fungal strains isolated from plastic waste showed the highest degree of plastic degradation. The present study provided novel fungal strains for low-density plastic degradation and has found huge potential to minimize plastic pollution.
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