Biological Degradation of Plastic Pollution

The Lake of Shining Water is beautiful to see. You went there but saw plastic bottles, straws, single-use plastic material, and many more. YES, that’s something we encounter whenever we go out. Plastic pollution is a nightmare. It is no longer a secret that plastic has severe consequences on the environment. The policymakers are putting great stress on eradicating all the plastics from the planet. But, what will we do with one that already existed in the environment? Each year the world produces around 380 million tons of plastic. Managing plastic pollution is a significant concern that requires innovative solutions. This article will give you an insight into biological solutions to the plastic problem. Before this, let’s learn the magnitude of plastic pollution, its causes, and its impacts. 


Each year the world produces around 380 million tons of plastic.

What is plastic?

Plastic is a synthetic material that is obtained from polymers. There are different types of plastics. To name a few, PMMA, PE, PET, PVC, and PC are common. These materials are used to make various products around us, from toothbrushes to casings and jars to bottles. The plastic dump into the environment, usually with other waste material. A tiny fraction is reused and recycled. The waste material is ended up in oceans, lakes, and dumpsites. Plastic has enormous impacts on human health and the environment. The microplastics became part of the food chain and caused deteriorating health impacts on each trophic level. Studies have found the effects of plastic pollution on the nervous system, endocrine system, and vital organs. Furthermore, the effects on marine animals cause their death. Single-use plastic products are a significant environmental issue that will have severe impacts in the future. 

 

Thank you to Edward Jenner and Pexels for image.
Thank you to Edward Jenner and Pexels for the image.

Management of plastic pollution requires innovative solutions. Treatment with the help of bacteria is one of them. Without further ado, let’s get into the topic. 

Principle of Degradation of Plastic:

 

The main principle of enzymatic degradation is as follows:

  1. Adsorption of enzyme on the surface of a polymer
  2. Hydrolysis of bonds that cause degradation of plastic polymer

Degradation of plastic by microbes is a promising solution for converting polymers into monomers for recycling or converting them into carbon dioxide, water, and raw material. Microorganisms that can hydrolyze the plastic could be found in soil, air, water, and wastewater. A study conducted by Yang in 2014 has shown that bacteria present in the gut of an excellent wax worm named Galleria melonella is capable of hydrolyzing polyethylene. Some other bacterial species can potentially degrade the PE after preliminary treatment, such as Ultraviolet and thermal treatment that renders biodegradation. These bacterial species are very commonly found, such as Bacillus spp. Rhodococcous spp. and Pseudomonas spp. Furthermore, some species of fungi, Aspergillus and Fusarium, could depolymerize the polyethylene. 

The degradation mechanism of PE occurs in four stages; Biodeterioration, Biofragmentation, Bio-assimilation, and mineralization. Different species of bacteria are involved in all these four stages. Certain bacterial species could degrade a specific type of plastic. For instance, P. aeruginosa metabolizes alkane hydrocarbons only.

 

Bacteria

Certain bacteria harbour the enzymes to degrade the plastic -PET. A study shows that the bacterium Ideonella sakaiensis convert PET plastic into biodegradable PHB. Thus, transforming the most problematic plastic into biodegradable plastic using bacterium is a sustainable approach to curb the plastic issue. 

 

Enzymes

Enzymes are an appealing solution for degrading plastic products. An extensive study was conducted in Japan to develop the plastic-eating enzyme. The study aimed to achieve the goal of reducing plastic pollution by using a cost-effective solution. The researchers found an unusual bacterium that has an uncontrolled appetite for plastic. A French company found out that enzymes could degrade 90 percent of plastic within 10 hours. This shows the potential of enzymes if employed for degradation. 

The plastic in natural environmental conditions took almost 50 years to discard. And in the ocean environment, it took even more time to degrade because of temperature variation and oxygen availability. PET-based plastic has high crystallinity with a low rate of microbial degradation. 

 

Invertebrates for Degradation of Plastic

Invertebrates are also used as a tool for combating plastic pollution. The digestive tract of some insects acts as a bioreactor where digestive enzymes and gut microbes accelerate the rate of biodegradation of plastic. Enterobacter asburiae and Bacillus species are found in the gut of the Indianmeal moth. These bacteria could degrade the 6-10% of plastic film and release ten different water-soluble products.

A study conducted in 2017 elaborated that larvae of greater wax moths have extraordinary ability to degrade polyethylene and convert it into ethylene glycol. The Enterobacter sp. D1 is responsible for the degradation. The discussion mentioned above has revealed that biological solutions have tremendous potential to combat worldwide plastic pollution. In recent years, a study has been conducted to discover the potential of Yellow Mealworms and snails to degrade the PE. Bacterial strains were isolated from the gut of mealworms that degrade the low-density polyethylene. However, it has been observed that biodegradation requires multiple microorganisms. 

 

Limitations

Despite all the innovations, biological solutions to the degradation of plastic pollution have certain drawbacks. One of them is sustaining the insect’s culture that could eat the PET. Secondly, maintaining the culture of insects requires a high cost. Thirdly, the microplastic could be formed that has severe impacts on the environment. The best way is to stop using plastic and substitute it with other materials. 

                             

 

 

Conclusion:

 

 

                               

 

 

Plastic is an artificial petroleum-based product. Each year, humans produce many plastics that are needed up in landfills and water bodies. These fragments of plastic pose severe impacts on human health and their environment. Disrupting the functioning of the endocrine system, neurological damage, reproductive system damage, and obesity are among the health impacts of plastic pollution. Different species of bacteria are employed for the degradation of plastic material. Several bacteria in the gut of invertebrates are helpful for this purpose. Nevertheless, they have some drawbacks as well. The best approach is to cut short our use of plastic to keep ourselves and the environment safe.