The Plastic Eaters

Isn’t it interesting to find any bacterial species that can eat plastic? The answer is obviously a ‘yes’ because the accumulation of plastic in the environment has created major environmental concern due its stability and non-biodegradability for thousands of years. The dumping of plastic on landfill is the major form of pollution caused due to it. The use of plastic made the daily life of human beings easier because of its strength, durability, affordability, reusability, and corrosion resistance which has led their movement in ground water, soil and sediments raising many concerns globally. Generally, the plastic wastes are either incinerated that generate various toxic gases or recycled which cannot be applied on the plastics mixed with other types of wastes. Also, the processing of plastic wastes dumped on landfills require large area. Therefore, an efficient and eco-friendly strategy is required for the decomposition of plastic pollutants from the environment. It appeared very hard for the scientists to find any microbe which can degrade plastics until 2016, when a group of scientists in Japan discovered a new species of bacteria that can degrade the plastic known as polyethylene terephthalate (PET). PET is a polyester thermoplastic which is used for the manufacturing of most disposable plastic water bottles. The scientist isolated the plastic degrading and assimilating bacterial species from sediment, soil, activated sludge and waste water from plastic bottles recycling site and named it as Ideonella sakaiensis 201-F6. This bacterial species was able to breakdown PET after adhering to its surface releasing two enzymes.

The one enzyme PET hydrolase (PETase) generated an intermediate product which was further broke down to another product by the action of enzyme MHET hydrolase (MHETase). The time required for the degradation of thin film of PET by Ideonella sakaiensis 201-F6 was 3 weeks at 30 °C temperature. Four bacterial strains, Bacillus amylolyticus, B.subtilis, Pseudomonas putida, and P. fluorescens have shown the ability to reduce 32%, 18%, 22% and 14% polyethylene (PE) film weight respectively when incubated in PE containing broth medium for a month. These bacteria utilize polyethylene polymer as a carbon source after breaking it down using an inducible operon system involved in the formation of enzymes such as serine hydrolase, esterase, and lipase required for the metabolism of carbon sources. All these findings show a great hope and potential for the biodegradation of plastics. However, several improvements need to be done in the existing process in order to increase the yield to apply it on the large contaminated land area