Relevance: GS-3: Conservation, Environmental Pollution, and Degradation, Environmental Impact Assessment.

Key Phrases: Microbes, plastic, recycling, Un-Plastic Collective (UPC), climate change, genome, biochemistry, enzyme, land pollution, food chain, habitat, microbiome, bioactive molecule.

Why in News?

• This deluge of plastic waste has grown exponentially over 60 years. Some 10 million tonnes of bottles, nets, bags, buckets, and food wrappings are dumped every year into waterways, where they entangle and kill marine life and damage the organs of the creatures, including, possibly, humans, that ingest them.

Impact of plastic pollution:

• Harmful to human health: Toxic chemicals from plastic bags can damage the blood and tissues. Frequent exposures can lead to cancers, birth defects, impaired immunity, hormone changes, endocrine disruption, and other serious ailments.
• Land Pollution: When plastic is dumped in landfills, it interacts with water and forms hazardous chemicals which degrade the groundwater. The wind carries and deposits plastic from one place to another, increasing the land litter.
• Effects of plastic on marine life: The most visible and disturbing impacts of marine plastics are the ingestion, suffocation, and entanglement of hundreds of marine species. Marine wildlife such as seabirds, whales, fishes, and turtles, mistake plastic waste for prey, and most die of starvation as their stomachs are filled with plastic debris.
• Impact on Habitats: Seafloor plastic waste sheets could act like a blanket, inhibiting gas exchange and leading to anoxia or hypoxia (low oxygen levels) in the aquatic system, which in turn can adversely affect the marine life.
• Interference with the Food Chain: Studies determine that the chemicals affect the biological and reproduction process resulting in reduced numbers of offspring thus disrupting the food chain.
  • When the smaller animals (planktons, mollusks, worms, fishes, insects, and amphibians) are intoxicated by ingesting plastic, they are passed on to the larger animals disrupting the interrelated connections within the food chain.
• Climate change: Plastic, which is a petroleum product, also contributes to global warming. If plastic waste is incinerated, it releases carbon dioxide into the atmosphere, thereby increasing carbon emissions.

Problems with Recycling of plastic:

• For 70 years, the world has been trying to recycle plastic without much success.
• Some experts believe that this will never truly work, in large part because there are many different types of plastic and they generally can’t be recycled together.
• Also, recycling is still more expensive than manufacturing new plastic; the plastics industry is expected to produce three times as much plastic in 2040 as it does today.

Need for a chemical enzyme to recycle plastic:

• Plastic has become so enmeshed in our ecosystem that bacteria have evolved to digest it and these might now offer a ray of hope.
• A key barrier to cost-effective recycling is finding chemical enzymes able to break down plastic quickly, recovering the molecules originally used to make it, a crucial initial step for re-use.
• By studying these plastic-eating bacteria, scientists have discovered some enzymes able to break down plastics far faster than was possible a decade ago.
• That’s a big advance from traditional recycling, which uses heat to melt plastic, leading to degraded and less useful material.
• Having shown the new technique, a firm in France expects to soon be recycling 50,000 tonnes of plastic each year.
• The greater hope for breakthroughs in recycling chemistry comes from our current spectacular ignorance of the microbiology of the seas and the genomics and computing technology that’s gearing up to change that.

Potential of the microbial universe:

• There is very little knowledge available about the world’s microbes.
• When biologists study the genetic content of seawater samples, two-thirds of what they find is unlike anything from known organisms.
• Some 99% of the genes identified in random samples of topsoil are not found in databases of known microbial genes.
• The microbiome - the universe of all microbial organisms—is a treasure chest of chemical leads about possible new drugs and other potentially useful biochemical compounds.
• The recent study alone found more than 40,000 new biosynthetic gene clusters—biologists’ term for small clusters of associated genes that together help produce some particular bioactive molecule. For scientists, these are prime candidates in the search for new and useful pharmaceutical compounds.
• Such studies are also helping scientists identify new enzymes able to digest plastics.
• In a study published last year, researchers identified plastic-degrading enzymes in the genomes of many bacteria, including those in the ocean and soils.
• Among the ocean bacteria, they also noted a strong correlation between the diversity of such enzymes and the amount of local plastic pollution.

Evolving biochemistry : A ray of hope

• In the brief 60 years that such pollution has been there, bacteria already have responded by evolving biochemistry to digest plastic as a food source.
• Bacterial engineering offers clues about how the science might produce better enzymes for recycling.
• From the bacterial research data, using modern genomic methods and machine learning, the researchers were also able to identify more than 30,000 new candidate molecules expected to have powerful plastic-digestive properties for at least 10 different types of plastic.

Conclusion:

• There is a need for much stronger commitments from governments to tax plastic packaging and encourage packing alternatives that use less plastic, or don’t use at all.
• If we take these steps, it isn’t too crazy to hope that, in 10 or 20 years, armed with more knowledge of the marine microbiome, scientists may find their way to a set of enzymes able to rapidly digest the many kinds of plastics industry might produce.
• If that happens, there could be hope for the oceans after all.

Source: Live-Mint

Mains Question:

Q. What are the impacts of plastic pollution on marine life and the environment? Explain how genomic study advancements may help beat plastic pollution?