J. K. Anuradha De Silva^1*, G. A. U. Jayasekera² and C. M. Nanayakkara<sup>1

1</sup>Department of Plant Sciences, University of Colombo, 00300, Colombo, Sri Lanka.
²Department of Agriculture Technology Science, Faculty of Technology, University of Colombo, Sri Lanka.

 

Municipal Solid Waste (MSW) is becoming a significant potential threat to the environment in Sri Lanka. Among the constituents of MSW, low density polyethylene (LDPE) is one of the most considerable portions of total waste generated, because it takes a long time to degrade naturally. Hence, this study mainly focused on identifying efficient fungal degraders of LDPE. To isolate the abundant fungi degrading polyethylene, partially degraded polyethylene were collected from different places in Kaduwela area, surface sterilized and placed on streptomycin incorporated PDA. Three fungi were isolated and purified. For biodegradation studies, these fungal isolates were inoculated on streptomycin incorporated ¼ strength potato dextrose agar medium which comprised 20 micron LDPE film and five replicates were used. After 90 days of incubation, gravimetric analysis, microscopic images, Fourier- Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) were conducted to determine whether there exists any potential in degrading LDPE by using these fungal isolates. These fungal isolates were identified using molecular identification tools. Multiple alignments of partial sequence were performed by CLUSTAL W and the phylogenetic was analyzed using MEGA 6.0 software. According to the One-way Analysis of Variance, the mean values for control and Penicillium sp. (P=0.000), control and Fusarium sp.KC-2010ba (P=0.031) and control and Penicillium sp.X9 (P=0.010) were significantly different. Scanning Electron Microscope (SEM) images and light microscopic observations revealed the presence of fungal colonization indicating surface erosion, cracks, folding and firm fungal attachment. The FTIR spectroscopy images of Fusarium sp. KC-2010ba and treated LDPE films showed the degradation initiating bonds such as carboxylic and aldehyde bonds. The fungal isolates were identified as Fusarium sp. KC-2010ba, Penicillium sp. and Penicillium sp. X9 by analyzing the ITS region sequencing. Therefore, it can be concluded that the fungal species Fusarium sp. and Penicillium sp. are capable of degrading and colonizing and has the potential to be developed into an inoculum for expedited LDPE degradation.

Key words: MSW, Biodegradation, Penicillium, Fusarium, SEM.