Pune: The solution to the plastic problem remains elusive. However, Prof Avinash Ade and his two doctoral students Manisha Sangale and Mohammad Shahnawaz have identified fungi which can degrade the polythene polymer element in the plastics.
Recently, the paper by the trio got published in the Nature magazine.
While talking to Sakal Times, Prof Ade said, “Among the 109 fungal isolates that we obtained, Aspergillus terreus strain and Aspergillus sydowii strain have been found to be the most efficient polythene degraders.”
Polythene contributes around 64 per cent of the total plastic waste and takes about 1,000 years to degrade under natural conditions. Despite a ban, the single-use polythene bags are still being used widely.
Ade said, “We carried out the research at the mangroves. The polythene strips were placed in petri dishes containing the fungi and were subjected to regular shaking at room temperature. Primarily, reduction in weight and tensile strength of polythene after this period was chosen as criteria for assessing degradation efficiency of the fungi.”
Ade said, “Aspergillus terreus showed 50 per cent weight loss of polythene while Aspergillus sydowii showed 94 per cent reduction in tensile strength of polythene.”
“After screening, the most efficient polythene degrading fungi were analysed using Scanning Electron Microscopy and Fourier-transform infrared spectroscopy (FTIR) to confirm the level of polythene degradation,” he said.
However, the mechanism of degradation is not yet known. “We are seeking to get an insight into the enzymes acting upon polythene and genes involved in its degradation. We are also exploring other fungi for degradation of another type of plastic, Polyvinyl Chloride (PVC),” he added.
A total of 109 fungal isolates were recorded from the collected rhizosphere soil (soil near the roots of the tree). Potential polythene degrading fungi were screened on the basis of reduction in weight (per cent weight loss: %WL) and tensile strength (per cent loss in tensile strength: % loss in TS) of the polythene after 60 days of incubation at ambient temperature with continuous shaking.
“Among the 109 fungal isolates, Aspergillus terreus strain MANGF1/WL (more than 50.00±4% WL, pH 9.5) and Aspergillus sydowii strain PNPF15/TS (94.44±2.40% loss in TS, pH 3.5) were found to be the most efficient and elite polythene deteriorating fungi based on reduction in weight, reduction in tensile strength, SEM and FTIR analysis. SEM analysis of the surface of the degraded polythene showed disturbances such as cracks, scions, fissures and holes which confirmed the
corrosion,” he explained.