Microbial Biotechnology in Environmental Applications microbiologystudy

Microbial biotechnology is widely used to clean up contaminated environments, degrade pollutants, and produce green and sustainable energy using microorganisms.

The various environmental applications of microbial biotechnology are discussed below:

The term bioremediation describes the process of utilizing microorganisms to eliminate or degrade contaminants or pollutants from contaminated air, water, and soil.  The microorganisms frequently employed in bioremediation are algae, fungi, and bacteria. For example: The application of microorganisms like bacteria to breakdown of oil spills, fungi breakdown pesticides, and algae to breakdown heavy metals from wastewater.

The process by which microorganisms are used to break down the complex organic compounds into simpler, less harmful substances is called biodegradation.  It is used to treat a variety of pollutants including industrial waste, sewage sludge, and agricultural waste. For example: The application of bacteria is used to break down plastics, fungi to degrade cellulose, and algae to produce biofuels.

3. Biosorption

The process by which microorganisms are used to eliminate the contaminants from soil or water by binding them in their cell walls is called biosorption. It is used to remove various pollutants like heavy metals, dyes, and pesticides.  For example: The application of bacteria is used to remove the copper, zinc, lead, etc. from wastewater, fungi to remove from soil, and algae to remove mercury from water. 

4. Biofuels

The liquid or gaseous fuels which are made up of renewable sources like plant extracts such as forest products, agriculture bi-products, municipal trash, and crop residue are called biofuels. These biofuels can be used to substitute the traditional petroleum based fuels used in vehicles and reduce the emissions of greenhouse gases (GHGs). Thus due to the lower emissions by biofuel combustion, it supports sustainability in the ecosystem. Biofuels can also be used to produce electricity. For example: Ethanol, Biodiesel, and biogas.

5. Bio-fertilizers

The process of employing microorganisms in soil, plant surfaces, or seeds that colonize the rhizosphere or the innermost part of the plant and stimulate the growth of the plant by providing nutrients is called bio-fertilizers.  Bio-fertilizers promote sustainable agriculture and reduce the dependency on chemical fertilizers. They can also improve soil fertility, enhance crop production, and reduce environmental pollution. For example:  

• Microbial nitrogen fixers (e.g., Rhizobium, Azospirillum, Azotobacter) convert atmospheric nitrogen into a form that plants can absorb.
• Phosphate solubilizing microorganisms (PSMs) convert insoluble phosphorus into a soluble form that plants can utilize.
• Potassium solubilizing bacteria and fungi release potassium from mineral forms, making it available to plants.
• Mycorrhizal fungi form symbiotic associations with plant roots, enhancing nutrient uptake (especially phosphorus, zinc, manganese, and copper) and water absorption.
• Plant growth-promoting rhizobacteria (PGPR) produce plant growth hormones and other beneficial compounds that promote plant growth and health.
• Cyanobacteria are photosynthetic microorganisms that can fix atmospheric nitrogen and enrich soil with organic matter, making them valuable bio-fertilizers in rice paddies.

6. Biopesticides

The process of using living organisms or any organisms that are generated from natural materials such as animals, plants, bacteria, and other minerals that stop the pest’s growth that harms human health or the farming industry is called biopesticides. It can develop modest adverse effects contrasting to chemical insecticides. For example: 

• Bacterial biopesticides (e.g., Bacillus thuringiensis) produce toxins that are harmful to specific insect pests.
• Fungal biopesticides (e.g., Beauveria bassiana, Trichoderma spp.) parasitize and kill insect pests.
• Viral biopesticides (e.g., baculoviruses) infect and kill specific insect pests.
• Nematode-based biopesticides use beneficial nematodes to parasitize and kill insect pests.
• Mechanisms of pest/pathogen control: Biopesticides can control pests and pathogens through various mechanisms, including toxin production, parasitism, competition, and induced plant resistance.
• Formulation and application methods for biopesticides: Biopesticides are available in various formulations (e.g., powders, liquids, granules) and can be applied through different methods (e.g., spraying, dusting, drenching).
• Regulatory considerations and safety of microbial biopesticides: Microbial biopesticides are generally considered safer than chemical pesticides, but they still require careful regulation and risk assessment to ensure their safe use.

7. Bioenergy Production

The organic materials (biomass) present in plants (carbonaceous materials) are utilized to produce energy during combustion which then carbon-dioxide (CO₂) gets released into the atmosphere is called bioenergy production.  It is one of the renewable energy sources with nearly zero-emission fuel and helps to reduce greenhouse gas emissions on the environment.  For example:

• Hydrogen-producing bacteria and algae can produce hydrogen gas through various metabolic pathways.
• Fermentative hydrogen production (dark fermentation): Organic compounds are fermented by anaerobic bacteria to produce hydrogen.
• Photobiological hydrogen production (using photosynthetic microorganisms): Photosynthetic organisms can produce hydrogen using light energy and water.
• Bioreactors for large-scale hydrogen production: Bioreactors are used to cultivate hydrogen-producing microorganisms on a large scale.
• Genetic engineering to enhance hydrogen production pathways: Genetic engineering can be used to modify microorganisms to improve their hydrogen production efficiency.

8. Bioethanol production

The form of renewable energy sources which is made from a variety of sources (food crops, biomass, and algae) and converted into fuel products is called bioethanol production. It is one of the eco-friendly and sustainable technologies that help in the reduction of greenhouse gas emissions and has become a substitute for environmental crises.  It is employed as an additive to petrol which involves the microbial fermentation of carbohydrates to ethanol.  For example:  

• Microbial fermentation of sugars to ethanol: Sugars from various sources (e.g., corn, sugarcane, agricultural waste) are fermented by microorganisms (e.g., Saccharomyces cerevisiae, Zymomonas mobilis) to produce ethanol.
• Cellulosic ethanol production: Lignocellulosic biomass (e.g., wood, agricultural residues) is broken down into sugars using enzymes and then fermented to produce ethanol.
• Pretreatment methods for lignocellulosic biomass: Pretreatment methods are used to break down the complex structure of lignocellulosic biomass and make the sugars accessible to microorganisms.
• Consolidated bioprocessing (CBP): CBP involves using engineered microbial strains that can both degrade lignocellulosic biomass and ferment the sugars into ethanol.
• Optimization of microbial fermentation conditions for higher ethanol yield: Fermentation conditions (e.g., temperature, pH, substrate concentration) can be optimized to increase ethanol yield.

9. Biogas and Methane Production

Renewable energy, also called a secondary energy source which is produced by using biodegradable organic materials (plant extract, crop residue, animal dung, and human excreta) through anaerobic digestion is called biogas and methane production. It is primarily composed of methane (CH₄), carbon dioxide (CO₂), and a small amount of hydrogen sulfide (H₂S) gas with some moisture. The biogas production can be employed in the production of renewable electrical and heat energy. Similarly, the residual material from anaerobic digestion can be used as a bio-fertilizer.  For example:

• Anaerobic digestion: Microbial consortia (including methanogenic archaea) decompose organic matter in the absence of oxygen to produce biogas, which is primarily composed of methane.
• Methanogenic archaea and their role in methane production: Methanogenic archaea are the key microorganisms responsible for methane production in anaerobic digestion.

10. Bioelectricity Production

The process of production of electricity by employing microorganisms on the generation of electrons as a byproduct of their metabolism is called bioelectricity production. It is one of the sustainable energy sources which can be generated from waste materials.  It can also be utilized to treat the wastewater. For example:

• Microbial fuel cells (MFCs): MFCs are devices that use microorganisms to convert organic matter into electricity.
• Mechanisms of electron transfer in MFCs: Microorganisms in MFCs transfer electrons to an anode, generating an electrical current.
• Electrogenic microorganisms: Microorganisms that can generate electricity in MFCs (e.g., Geobacter, Shewanella spp.)

11. Biodegradable Plastics and Microbial Products

The plastics that can break down into water, carbon dioxide, and biomass with the help of microorganisms are called biodegradable plastics. The biodegradable plastics are the mixtures of petrochemicals, microorganisms (bacteria, fungi, and algae), and renewable mixtures. For example: 

• Polyhydroxyalkanoates (PHAs): PHAs are a class of biodegradable plastics produced by bacteria (e.g., Ralstonia eutropha).
• Microbial synthesis of polylactic acid (PLA): PLA is another biodegradable plastic that can be produced by microorganisms.

Summary of Environmental Biotechnology Applications

1. Wastewater treatment: Microorganisms can be utilized to treat wastewater by decomposing down organic matter, eliminating contaminants, and producing clean water.
2. Soil remediation: Microorganisms can be employed to clean up contaminated soil by breaking down pollutants or immobilizing them.
3. Air pollution control: Microorganisms can be utilized to eliminate pollutants from the air, such as volatile organic compounds (VOCs) and greenhouse gases.
4. Bioremediation of hazardous waste: Microorganisms can be utilized to degrade hazardous pollutants such as polychlorinated biphenyls (PCBs) and dioxins.
5. Production of bioproducts: Microorganisms can be utilized to produce a variety of bioproducts, such as enzymes, antibiotics, and biofuels.



Challenges and Future Directions of Microbial Biotechnology

Challenges

• It is necessary to develop more efficient and cost-effective bioremediation technologies for developing countries like Nepal. 
• It is better to understand the mechanism of microbial degradation to assure the safety and sustainability of these technologies. 

Future directions

• The development of novel microbial strains for bioremediation, 
• The use of genetic engineering to enhance microbial capacity for bioremediation, and 
• The integration of microbial biotechnology with other technologies, like nanotechnology and biotechnology.

Conclusion

Thus, in the recent scenario of having contamination all over the environment including soil, water, and air, biotechnological application can be the best and most efficient way to remediate it and eliminate the pollution. 

References

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