Remediation And Control Of Regional And Global Environments By Soil Micro-Organisms




An immense increase in the world population has given rise to industrialization for feeding the demands of this number of people. This has led to the discharge of several noxious waste residues that create severe problem to both plants and animals. Heavy metal contaminants are of one of these, and are basically produced in the form of effluents from industries as well as agricultural wastes, originated from overexploitation of chemical fertilizers and pesticides. These contaminants are polluting the arable land indirectly affecting nations’ economies by simultaneous degradation of soil fertility, ultimately reducing the crop productivity. Because of this situation hunger is not very far from us; to avoid this and improve the health of soil, two methods can be taken into consideration.

Increase the productivity and quality of agricultural production.
Reduce the concentration of heavy metal contamination from the soil.

For both methodologies, soil involvement is most important step. The first one implicates a group of beneficial microflora, PGPR, which enhance plant growth and development with sustainable improvement in soil fertility. These microbes also play a crucial role in soil remediation by improving soil health. This involves several mechanisms, including:

Phytohormone production
Siderophores production
Phosphate solubilization
Induced systemic resistance
Nitrogen fixation

The second methodology incorporates the reduction of heavy metal pollutants from the soil, ultimately improving the quality of soil by physical, chemical, and biological means of remediation. Physical remediation employs a specific area by treatment of contaminated soil such as replacement of polluted soil by pure and healthy soil. Chemical remediation deals with the inoculation of chemical agents to make contaminants less toxic, movable, and easily soluble. But both processes cannot beundertaken due to the specificities. To avoid the side effects and make the environment eco-friendly, the biological method of remediation is coming into practice. Biological remediation is also listed as phytoremediation, which is classified into three subclasses: phytoextraction, phytovolatilization, and phytostabilization. The most promising and newly growing field of biological remediation is the inoculation of PGPR along with the green plants of higher accumulation and absorption efficiency.

Despite the advancement of diverse techniques in the field of plant–microbe interactions, which reach plant growth and development along with the suppression of pathogens, their implications in the field of soil remediation are still in the nascent stage. To exploit the promising advancement of PGPR, it has become essential to raise our understanding regarding the application of PGPR–plant interaction. Recently, research has focused on the detoxification of heavy metal contaminants and their concentration in the soil by absorbing nutrients through roots. Actually, on interaction of PGPR with plants, the defense mechanisms of plants increased synergistically, improving the soil quality. These beneficial microorganisms improve the production of crops along with the betterment of soil and suppression of pathogenic organisms through diverse mechanisms, such as by producing growth hormones, bio-control agents, ISR, Systemic acquired resistance (SAR), nitrogen fixation, phosphate solubilization, and siderophores production. Some PGPR have the ability to remediate heavy metal contaminants through the green plants in the environment by phytostabilization, phytovolatilization, and phytoextraction. Some exciting results also recommended the usefulness of PGPR, specially siderophores, an important metabolite found to potentially be active in transportation and accumulation of heavy metal pollutants.

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