Genetic Engineering has widely been applied in bioremediation procedures recently. It involves the application of genetically engineered microorganisms to contaminated sites for the management and remediation of these contaminants. The use of genetically altered organisms for bioremediation would be an environmentally benign and cost-effective option. Recombinant DNA and RNA technologies have been used to create various types of genetically engineered bacteria that have been used to remove heavy metals and hazardous compounds from contaminated locations. The effectiveness of bioremediation of contaminated places can be improved by a symbiotic connection between genetically altered bacteria and transgenic plants. This involves techniques such as phytoremediation and its types. This article will explain to you the Genetic Engineering Approaches which will be helpful in preparing the Environment Syllabus for the UPSC Civil Service exam.

What is Genetic Engineering?

• Genetic engineering is the technique of modifying the genetic makeup of a host organism by utilizing recombinant DNA Technology (rDNA Technology).
• It involves using a vector to transfer isolated DNA from the donor organism to the host organism.
• Vectors should be able to replicate inside their hosts without causing any changes to their genetic makeup.
• Many different bacteria are employed in genetic engineering investigations, but Escherichia coli (E. coli) and Agrobacterium tumefaciens are two of the most common bacteria used.
• In the fields of biotechnology and genetic engineering, E. coli is one of the most commonly employed microorganisms.
• E. coli has a quick generation time and is capable of producing a large number of plasmid copies with high fidelity.
• The creation of human insulin is one example of using E. coli in genetic engineering.
• Similarly, the naturally occurring bacteria Agrobacterium tumefaciens has the ability to infect plants and transmit some of its own DNA. As a result, they can be employed to transmit the desired gene.

Genetic Engineering Approaches

Phytoremediation

• Living plants are used in phytoremediation technologies to clean up soil, air, and water that have been contaminated with dangerous pollutants.
• It's defined as "the employment of green plants and associated microbes and appropriate soil amendments and agronomic techniques to either contain, remove, or render harmful environmental toxins harmless."
• Many plants, including mustard, alpine pennycress, hemp, and pigweed, have demonstrated their ability to hyperaccumulate toxins at toxic waste sites.
• Phytoremediation has been used successfully to recover abandoned metal mine workings, sites where polychlorinated biphenyls were deposited during manufacturing, and mitigation of continuing coal mine discharges, decreasing pollutants in soils, water, and air.
• Metals, pesticides, solvents, explosives, and crude oil and its derivatives have all been reduced through phytoremediation operations around the world.

*To know more about the topic, click this link Phytoremediation

Phytoremediation - Types

Phytoextraction / Phytoaccumulation

• Phytoextraction/phytoaccumulation is the process by which plants accumulate pollutants in their roots, shoots, or leaves above ground.
• The roots absorb elements from the soil or water and concentrate them in the plant's biomass above ground.
• Hyperaccumulators are organisms that have a high capacity for absorbing pollutants.
• Phytoextraction has been rapidly gaining popularity around the world for the past twenty years or so. Heavy metals and other inorganics are commonly extracted via phytoextraction.
• Contaminants are often concentrated in a significantly smaller volume of plant matter at the time of disposal than in the initially contaminated soil or silt.
• Because a lower level of pollutants remain in the soil after harvest, the growth/harvest cycle must normally be repeated over several crops in order to achieve a meaningful cleanup. The soil is then remediated as a result of the procedure.

Phytotransformation/ Phytodegradation

• Phytotransformation, also known as phytodegradation, is the transformation of organic pollutants from soil, sediments, or water into a more stable, less hazardous, and less mobile form.
• The plant roots secrete enzymes that break down the organic chemicals, which are subsequently taken in by the plant and expelled by transpiration.
• Herbicides, trichloroethylene, and methyl tert-butyl ether are among the organic pollutants that this method works best with.
• The chemical change of environmental compounds as a direct result of plant metabolism is known as phytotransformation, and it frequently results in their inactivation, degradation (phytodegradation), or immobilization (phytostabilization).
• Organic pollutants, such as pesticides, explosives, solvents, industrial chemicals, and other xenobiotic compounds, are rendered non-toxic by the metabolism of certain plants, such as Cannas.
• In other cases, these compounds may be metabolized in soil or water by microbes living in close proximity to plant roots.

Phytostabilization

• Phytostabilization is a process in which plants limit contaminated soil movement and migration.
• Adsorbed and bonded into the plant structure, leachable elements form an unstable mass of plant from which toxins cannot re-enter the environment.
• By attaching contaminants to soil particles, the plant immobilizes them, making them less available for plant or human uptake.
• Phytostabilization, unlike phytoextraction, concentrates on sequestering contaminants in the soil near the roots rather than in plant tissues.
• As pollutant bioavailability decreases, exposure decreases.
• Plants can also excrete a material that causes a chemical reaction, resulting in the heavy metal pollution being converted to a less harmful form.
• Stabilization reduces erosion, runoff, and leaching while also lowering the contaminant's bioavailability.
• The use of a vegetative cap to stabilize and contain mining tailings is an example of phytostabilization in action.

Rhizodegradation/ Phytostimulation

• Rhizodegradation, also known as phytostimulation, is the breakdown of pollutants through rhizosphere activity.
• The presence of proteins and enzymes produced by plants or soil organisms such as bacteria, yeast, and fungi is responsible for this action.
• These bacteria may degrade dangerous contaminants like fuels and solvents into benign and harmless products.
• Plants release natural carbon-containing compounds such as sugar, alcohols, and acid, which provide additional nutrition to microbes and increase their activity.
• Transgenic plants with better plant-microbe interactions have potential to produce.
• The plant's ability to release natural chemicals that drive microbial activity would be improved.

Rhizofiltration

• Rhizofiltration is a method of removing harmful chemicals and surplus nutrients from water by filtering it through a mass of roots.
• Pollutants are absorbed by the roots or transferred on them.
• This method is frequently used to clean up contaminated groundwater by either planting directly in the contaminated area or extracting the contaminated water and delivering it to these plants off-site.
• Plants are normally grown in a greenhouse under controlled conditions in either situation.
• This technique is used for reducing pollution in wetlands and estuaries.

Mycoremediation

• Mycoremediation is a type of bioremediation in which fungi are utilized to clean up a site.
• Fungi have been shown to be a cost-effective, ecologically friendly method of eliminating a wide range of toxins from contaminated settings or wastewater.
• In land, fresh water, and marine ecosystems, these contaminants include heavy metals, organic pollutants, textile dyes, leather tanning chemicals and wastewater, petroleum fuels, polycyclic aromatic hydrocarbons, pharmaceuticals and personal care products, pesticides, and herbicides.
• Byproducts of the remediation process, such as enzymes, edible or medicinal mushrooms, can be valuable resources in and of themselves, making the remediation process even more profitable.
• Some fungus can help with the biodegradation of pollutants in extremely cold or radioactive situations, where typical cleanup procedures are either too expensive or impossible to utilize due to the severe conditions.

*To know more about the topic, click this link Mycoremediation

Mycofiltration

• Mycofiltration is a similar method that filters harmful waste and germs from water in soil using fungus mycelium.
• In the remediation of pollutants/xenobiotics, fungal mycelium is reported to use methods such as biosorption, bioaccumulation, and biodegradation.
• Several fungus species have been examined and found to have outstanding ability to absorb and remove metals and other contaminants from waste and/or runoff water.
• Fungal species, whether alive or as dried biomass, have a high biosorption capacity for metals like Cu, Zn, Fe, and Mn, as well as the ability to change resistant medicinal compounds and break down insecticides.

*To know more about the topic, click this link Types of Phytoremediation

Genetic Engineering Approaches - Advantages

• Maintain Fertility: It maintains the soil's fertility by preserving the topsoil.
• Boost Soil Health And Yield: Boost soil health, yield, and phytochemicals in plants.
• Prevents Soil Erosion And Leaching: Plants also help to prevent soil erosion and metal leaching.
• Bacterial Benefits: The bacteria employed here are good at controlling smell, lowering BOD, and preventing the buildup of oil or grease in sewage/polluted water and solids.
• Wide Temperature Range: These microbial consortia can flourish in a wider range of temperatures.
• Low Powered Aerators: Because these strains maintain a suitable amount of dissolved oxygen (DO), aerators that require a lot of power can be avoided or used less.

Disadvantages

• Applicable Only to Biodegradable Substances: Only biodegradable substances are allowed.
• Longer Stay Of Biodegradation Products: Some people are concerned that the biodegradation products would stay longer or be more harmful than the parent chemical.
• Longer Treatment: It takes a lot longer than other treatment methods like pyrolysis or incineration.
• Tougher Operations: Inferring from bench and pilot-scale investigations to full-scale field operations is tough.

Conclusion

Thus, plant breeding initiatives and genetic engineering can be used to improve natural phytoremediation capabilities or introduce new capabilities into plants. Phytoremediation genes can come from a microorganism or be transferred from one plant variety to another that is more suited to the cleanup site's environmental circumstances. Genes encoding a nitroreductase from a bacteria, for example, were put into tobacco and exhibited faster TNT elimination and increased tolerance to TNT's harmful effects. Plants have also been shown to have a system that permits them to flourish even when the pollution level in the soil is too high for non-treated plants to survive. Exogenous polyamines, for example, are natural, biodegradable molecules that allow plants to endure pollution concentrations 500 times greater than untreated plants.