Caterpillar could be a solution to plastic pollution

Scientists say the larva of the common insect Galleria mellonella or greater wax moth has been found to break down the chemical bonds of polyethylene which is highly resistant to breaking at high speeds. The accidental discovery could lead to the biodegradable solution to the plastic which is a major threat to our ecosystem or environment.

Cambridge: As the world’s population is continuing to grow, so is the garbage.  Plastic is one of the most widely used material in today’s world. As plastic is composed of major toxic pollutants, it has potential to cause great harm to the environment in the form of air, water and land pollution. Polyethylene is the most commonly used plastic in the world. About 80 million tons of plastic is made annually. It is largely utilized in packaging. Nearly 50% of polyethylene is used to produce plastic films for food storage as well as agricultural and environmental use and the rest is used to produce plastic bottles. Due to the chemical structure of polyethylene which is highly resistant to breaking down and when it does, its remains choke up ecosystem without degrading. The harm to the environment is heavy. Every minute, two million plastic bags are used throughout the world. Most of these bags are thrown away within 20 minutes and end up in a landfill or in the open environment.

New   Research

Where the world is searching for biodegradable alternatives for plastic, a latest research finding can be a major asset for the whole world. The caterpillar which is identified as a “wax worm” or “plastic eating caterpillar” is the key to a solution for plastic waste. An international team of researchers from Spain and the United Kingdom has found that a caterpillar Galleria mellonella, commonly known as a wax worm has the ability to biodegrade polyethylene.

The discovery took place when a member of a scientific team, Federica Bertocchini, an amateur beekeeper & biologist in the Institute of Biomedicine and Biotechnology of Cantabria University (CSIC), Spain, noticed the caterpillars chewing the plastic while removing the parasitic pests from the honeycombs in her hives. Bertocchini temporarily kept worms in a typical plastic shopping bag that became riddled with holes in a very short time. Further, Bertocchini collaborated with colleagues Paolo Bombelli and Christopher Howe at the University of Cambridge’s Department of Biochemistry to conduct an experiment.

The research team let those caterpillars there for 12 hours and was amazed to see the results when there was a huge reduction of the plastic mass after all that munching. The study showed that the wax worms were not only ingesting the plastic, they were also chemically transforming the polyethylene into ethylene glycol.  This happened in the case of Plodia interpunctella as well. Experiments conducted before showed that Plodia interpunctella wax worms, the larvae of dian mealmoths, can also digest plastic.

Although wax worms wouldn’t normally eat plastic, the researchers suspect that their ability is a by product of their natural habits. Wax moths lay their eggs inside beehives. The worms hatch and grow on beeswax, which is composed of a highly diverse mixture of lipid compounds. The researchers said, “The molecular details of wax biodegradation require further investigation, but it’s likely that digesting beeswax and polyethylene involves breaking down similar types of chemical bonds. After the molecular details of the process become known, the researchers say it could be used to devise a biotechnological solution to managing polyethylene waste.”

The Scientific Process

Beeswax is made of a wide variety of compounds, including alkanes, alkenes, fatty acids and esters. Many of those compounds include carbon-carbon bonds, which could mean the wax moth has a natural talent for breaking those down. The researchers conducted deep analysis to show the chemical bonds in the plastic were breaking. The analysis showed the worms transformed the polyethylene into ethylene glycol, representing un-bonded ‘monomer’ molecules. Scientists were skeptical if caterpillars were just chewing the plastic or actually degrading it. To confirm this, the team mashed up some of the worms and smeared them on polyethylene bags, with similar results.

According to the report scientist ‘Paolo Bombelli’ (one who is working on this) said, “The caterpillars are not just eating the plastic without modifying its chemical make-up. It shows that the polymer chains in polyethylene plastic are actually broken by the wax worms. The scientists suspected that caterpillar produces something that breaks the chemical bond, perhaps in its salivary glands or symbiotic bacteria in its gut. The next steps for us will be to try and identify the molecular processes in this reaction and see if we can isolate the enzyme responsible.”

Every year, factories around the world produce about 88 million tons of polyethylene. Although it’s used widely-the average person uses about 230 plastic bags annually – the material is slow to degrade. “The low-density polyethylene used in plastic bags can take about 100 years to decompose completely, and the most resistant polyethylene products can take up to 400 years to decompose”, the researchers said.

Chemical degradation is a solution for this but process can take months and uses corrosive liquids, including nitric acid. So the caterpillar discovery is the first solution ever which can biodegrade polyethylene naturally.

According to a report published Bertocchini says, “We are planning to implement this finding into a viable way to get rid of plastic waste, working towards a solution to save our oceans, rivers, and all the environment from the unavoidable consequences of plastic accumulation.”

Caterpillars are not only eating the plastic without modifying its chemical make-up but the polymer chains in polyethylene plastic is actually broken by the wax worms.

Hope to the World

Past attempts to use living organisms to get rid of plastics have not gone well. Even the most promising species, a bacterium called Nocardiaasteroides, takes more than six months to obliterate a film of plastic a mere half millimetre thick. But, according to the experiment conducted on these wax worms, it gives us a ray of hope.

Where the whole world is engaged in searching for a solution to the problem of plastic, these “plastic eating caterpillars” are very encouraging. The accidental discovery has immense potential and is an exciting step towards a possible solution to the worldwide plastic problem. When we see at a ground level, a large scale implementation of this discovery will take some time, but if implemented, it will surely a biodegradable  solution to the world.