Pratibimba 2019 Pratibimba 2019 | Page 38

k|ltlaDa Nature reflects our nature Can plastics be degraded ? My hands are on the keypad of my laptop and I am typing by pressing those small keys and I am aware that I am using a device with many parts of it made by Plastics. Plastic mostly related to words like Pli- able (Stretchable, malleable) and Polymers (of many parts) has become an indispensable part of our life. It is used in each part with which we strike time and again in our daily life. Annually we manufacture about 3 mil- lion ton of plastics. Looking at the statistics of 2017, world plastics production totaled around 348 million metric tons and the rate of manufacture is growing exponentially. The plastics (Focusing; Polyethylene terephthalate (PET)) comes with the packaging of clothes, utensils, mineral water, drinks, other devices (laptop, pen, watches, etc.) and vast use in scientific discovery and other technical fields. These products are most essential for us so we can agree that the plastics are used for the vital works but what about the work done by the plastics towards the environment? In a cycle of nature everything dies, deteriorates once to keep up the balance but what about plastics? Are Plastics that idiosyncratic stuff that violates this very ethic and lasts forever in the environment? The answer was yes before 2012 and was only believed to maintained by following 5R principles (Reduce, Reprocess, Reuse, Recycle, Recover) but by 2012 a group of Student from Yale University searched for plants within the Amazon and then cultured the mi- croorganisms within the plant tissues and ended up by finding pestalotiopsis, which could effectively de- grade polyurethane(used mostly in hard plastics and foam) and again in 2016 a team at Kyoto University had found a bacterium that degrades and assimilates poly(ethylene terephthalate)(General plastic bottles). By scrambling around sediments, soil, wastewater and other piles of wastes they took 250 samples in 5 years and isolated a bacteria “Ideonella Sakiensis” that can live on Plastics. The second discovery of 2016 was more effective in comparison with the first one as Ideonella Sakiensis could grow easily but it is not that easy to cultivate fungi pestalotiopsis. The student of Kyoto also identified the enzymes that are used by sakiensis to breakdown the PET. They iden- tified a gene in the DNA of bacteria that is responsi- ble for the production of PET degrading enzyme. The enzyme was named as PETase. The PETase can breakdown certain chemical bonds in PET, leaving tiny molecules that can be absorbed by bacteria us- ing carbon in them as a food source. Different groups of people of many countries like Korea, China, UK, and Brazil are in continuous research to find out the mechanisms of the enzyme and trying to make it work faster by manipulating its active parts. This is unusual that the enzyme that is being discovered should work faster than the natural one. But still, this achievement shows that these bacteria are recent- ly evolved to survive on the man-made plastic which can be an evolutionary approach to engineer an op- timized form of PETase. Despite the negative impact of plastics we mostly depend on Plastics and if the rate of enzyme formation increases then the durabili- ty of plastic products decreases. What if the bacteria started eating all the plastic struc- tures of the environment in an uncontrolled way that were made to last for the number of years? Will our survival become possible without any plastic prod- ucts? The situation can arise as we are not that good to outplay with bacteria. (Antibiotics example). But perhaps looking at today’s worst condition of Envi- ronment made by plastics, the identification of bacte- ria like Ideonella sakiensis can be a good fortune for all the living creatures. Samyog Dhakal B.Sc.Environmental Science 2nd Year (Batch-2017) Nature and Social Concern Society 38