Bioremediation of Heavy Metals and Other Toxic Substances by Microorganisms

Abstract

Bioremediation is an innovative and appealing alternative to physical and chemical methods for removal and recovery of heavy metals and toxic substances from polluted areas. This method involves the use of living organisms that are capable of either breaking down or transforming contaminates to less toxic or nontoxic elemental and compound forms. The potentiality of microorganism to degrade the pollutants is mainly attributed to their nutritional versatility and metabolic diversity, which can be exploited in the bioremediation process. Autochthonous microorganisms i.e., bacteria, fungi, yeast, and algae are capable of degrading and/or rendering these contaminants immobile in soil via adoptive mechanisms of biosorption, bioaccumulation, biotransformation, and biomineralization in order to aid their survivability in heavy metal contaminated soils. Several approaches of bioremediation include intrinsic bioremediation using indigenous microbes, biofilters, bioventing, and bioaugmentation /stimulation, which is explored either through in-situ or ex-situ methods. Recently, genetically engineered microorganisms have also shown potential for bioremediation applications in soil, groundwater, and activated sludge environments, exhibiting enhanced degradative capabilities encompassing a wide range of heavy metals and chemical contaminants. The generation of contaminations in the environment as a natural and continuous process cannot be avoided. However, adopting suitable remediation strategies can prevent its accumulation above the threshold limit. Bioremediation is a novel, cost-effective, and efficient strategy to reduce toxicity of heavy metal and other contaminants in the environment. A sustainable approach needs to be developed in order to select appropriate strains of microbes, operating conditions, and efficient mechanism thereby making the application of bioremediation most feasible. Also, the exploration of metal uptake potential and metabolic pathways of microbes needs further investigations to address waste management in the environment.