Question

Discuss the role that microbes could play in remediation of environmental pollution. (750-1000 words; 50%)

Answer 1

Role of microbes in remediation of environmental pollution :

Nowadays, one of the most important problem the world is facing is the environmental pollution. Microorganisms on the other hand, are essential for a key alternative solution to overcome this challenge. Microorganisms are survive in most of the places on the biosphere because of their metabolic activity and the nutritional capacity of microorganisms is completely varied, hence is used as bioremediation of environmental pollutants.

Bioremediation is a method of waste management which involves the use of organisms, especially microorganisms to remove or neutralize the pollutants from a contaminated site. Here, the nutritional versatility of microorganisms is exploited for the biodegradation of pollutants.

Bioremediators are those biological agents which are used for bioremediation process. Bacteria, archaea and fungi are the typical prime bioremediators.

In the process of bioremediation, the organic wastes are biologically degraded under controlled conditions to an innocuous state, or to levels below the concentration limits that have been established by regulatory authorities. Microorganisms are best suited for this task because, they possess enzymes which allows them to use the environmental contaminants as a food source. For the process to be effective, the microorganisms must enzymatically degrade the pollutants and convert them into harmless products. Biodegradation is the principle process behind bioremediation. It refer to the complete removal of organic toxic pollutants into least harmless or naturally occurring compounds like carbon dioxide, water, inorganic compounds those are safe for human, animal, plant and aquatic life.

Examples of microorganisms and the compound removed :

- Pseudomonas putida : Monocyclic aromatic hydrocarbons

- A. niger : Hydrocarbons

- Fusariumsp. : oil

- Bacillus cereus A : diesel oil

- Penicillium ochrochloron : industrial dyes

- Saccharomyces cerevisiae : Heavy metals, lead, mercury and nickel

Advantages of Bioremediation :

- It is a natural process. The residues after the treatment process are usually harmless product which includes water, carbon dioxide and cell biomass.

- The process requires much less effort and can often be carried out on site without causing any major disruption of normal activities. It also eliminates the need of transporting quantities of waste off site.

- It is an important method for the treatment of oil-contaminated sites.It is a cost effective process.

- The process also helps in the complete destruction of pollutants, most of the hazardous compounds can be transformed into harmless products.

- Does no use any harmful chemicals.

- Simple, less labor intensive and cheap for their natural role in environment. Is eco-friendly and sustainable.

Disadvantages of Bioremediation :

- The process is limited to compounds that are biodegradable. Not all the compounds are susceptible to rapid and complete degradation process.

- Are highly specific. Factors include the presence of metabolically capable microbial populations, suitable environmental growth conditions, and appropriate levels of nutrients and contaminants.

- The process takes longer than some of other treatment options like excavation and removal of soil or incineration.

Types of Bioremediation processes :

1. Biostimulation.

This method works by the injection of specific nutrients at the site (soil/ground water) to stimulate the activity of indigenous microorganisms.

2. Bioattenuation.

Bioattenuation or natural attenuation is a process in which the biodegradation process occurs naturally without human intervention.

3. Bioaugmentation.

Bioaugmentation is the process in which cultured microorganisms are added into the subsurface for the purpose of biodegrading specific soil and groundwater contaminants.

4. Genetically Engineered Microorganisms (GEMs).

These are microorganisms whose genetic material has been already been changed by applying genetic engineering techniques inspired by natural otherwise artificial genetic exchange between microorganisms. These organisms have shown potential for bioremediation applications in soil, groundwater, and activated sludge environments, exhibiting enhanced degradative capabilities including a wide range of chemical contaminants.

5. Bioventing

The process is involved in venting of oxygen through soil to stimulate the growth of natural or introduced bacteria and fungus in the soil by providing oxygen to existing soil microorganisms.