Role of microbial enzymes in bioremediation: Emerging opportunities and limitations

Due to massive industrialization and several other human activities, anthropogenic activities are leading to disastrous environmental conditions. The released toxic substances pollute the ecosystem and cause various disorders in living organisms, including humans, animals, and plants. Conventional methodologies of removing toxic pollutants are not effective enough to degrade or lower the amount of contaminants up to the standard levels. Bioremediation is a nature-friendly, efficient, and cost-effective method of eliminating hazardous toxic pollutants present in the ecosystem by applying microbial enzymes (biologically active metabolites). Microorganisms immobilize or degrade toxic pollutants by utilizing them as a substrate for their metabolic processes. In the process of bioremediation, microbial enzymes play a crucial role in degrading several organic and inorganic pollutants such as PAHs, polymers, azo dyes, organocyanides, chromium, lead, and mercury. The major microbial enzymatic classes comprise oxidoreductases, hydrolases, dehalogenases, and transferases that are responsible for the degradation of toxic pollutants. This chapter attempts to elaborate in detail information regarding the several biologically active enzymes of microbes used in the bioremediation of toxic pollutants, applications in the present scenario of microbial enzymatic remediation, limitations, and emerging opportunities.