In Vitro and In Silico Study of the Efficacy of Fungi in Low-Density Polyethylene Degradation in a Disposal Paper Cup

Seenivasagan, R.; Karthika, A.; Poonkuzhali, K.

In Vitro and In Silico Study of the Efficacy of Fungi in Low-Density Polyethylene Degradation in a Disposal Paper Cup

2022

Seenivasagan, R. | Karthika, A. | Poonkuzhali, K.

Low-density polyethylene (LDPE) is made from the monomer, ethylene. It is mainly used as food packing material and is difficult to recycle. Thus, we attempted to identify the fungal compositions from a plastic disposal site and use them to degrade LDPE. We identified five isolates as belonging to Rhizopus spp. and Aspergillus spp. according to their morphologies. The fungal isolates were tested using a biodegradation assay with LDPE-supplemented growth medium. Among the five fungal isolates identified, strain A effectively degraded LDPE as evidenced by its increased biomass and greater reduction of the LDPE weight (60%). PCR amplification of the 18S rRNA from genomic DNA isolation of this strain revealed that the strain had 96% similarity to Rhizopus oryzae according to BLAST searches. As an LDPE-degrading fungus, the sequence was submitted to GenBank under the accession number MT259131. Fourier-transform infrared spectroscopy and scanning electron microscopy analysis provided evidence for the functional group and morphological changes in the LDPE. We further substantiated its ability to degrade plastic by docking the LDPE and polyethylene terephthalate (PET) substrates with the chitinase enzyme from Rhizopus oryzae and a control enzyme. The docking scores for the chitinase enzyme (AAP57213) were − 7.0 kJ/mol for LDPE and − 6.7 kJ/mol for PET. The docking score for the control was − 5.5 kJ/mol. These results suggest that degradation of LDPE and PET helps with societal recycling of plastic waste.

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