Chapter 9 - Microbial enzymes in biodegradation of organic pollutants: mechanisms and applications

Abstract

The traditional physico-chemical methods tend to be highly energy- and reagent-consuming for pollutants removal, such as pesticides, dyes, halogenated compounds, and aromatic hydrocarbons. Sometimes, non-biological remediation may not be effective for decontamination, and the intervention usually significantly impacts the environment. Instead, biotechnology-based strategies are an environment-friendly approach. Bioremediation can be performed by microbial enzymes with high efficiency. Various microorganisms have been reported in the bioremediation of contaminants, but few strains have been investigated at the enzymatic level. Different enzymes have been employed in the biodegradation of a wide range of organic compounds. These enzymes are advantageous since they are nontoxic, biodegradable, highly specific to their substrates, and active at low concentrations. Besides, they are tolerant to inhibitors and act under mild pH and temperature conditions. Among them, laccases, peroxidases, oxygenases, dehalogenases, azoreductases, and hydrolases are highlighted by different mechanisms of action, such as oxidation, reduction, elimination, and ring-opening. This chapter summarizes the function of these enzymes, their catalytic pathways, applications, challenges, and perspectives to contribute to xenobiotic removal and environmental health.