Isolation and Screening of Actinomycetes for Biodegradation of Low Density Polyethylene from Mangrove Sediment

Polyethylene is widely used as a packing material for different purposes of human life. Accumulation of polyethylene in the environment may cause ecological threat. To prevent the accumulation of polyethylene in the environment, a total of seven actinomycetes were isolated from Koringa Mangrove sediments, near Kakinada, Andhra Pradesh. These isolates were able to grow on mineral salts medium containing polyethylene as a sole source of carbon. Of these, one isolate M4 showed prominent result with redox probe TTC (2,3,5-triphenyltetrazolium chloride) as a viability indicator, which forms red coloured insoluble TPF (triphenylformazan) on mineral salts medium containing emulsified polyethylene within five to seven days, and was selected for detailed analysis. A significant reduction in weight of the polyethylene films were observed after four weeks of incubation with selected isolate in the mineral salts medium containing PE films as a carbon source. The viability and metabolic activity of isolate M4 growing on the polyethylene surface was confirmed using a TTC reduction test. The microbial degradation of LDPE was also analyzed by the change in pH of the culture media and microscopic analysis. Optimization of pH and temperature range for polyethylene degradation by this isolate was studied. The isolate was also able to grow on other polymers such as polyvinyl acetate, polycaprolactone, polyethylene oxide and polyethylene glycol. It could be concluded that the PE degrading actinomycete isolate selected in this study showed diverse and varying capacities to degrade polyethylene and other polymers and can be exploited for cleaning up polyethylene contaminated sites.