Role of Microbial Enzymes in the Bioremediation of Pollutants: A Review

Table 1

Industrial applications of microbial enzymes.

SI No.	Enzyme	Substrate	Reaction	Applications
1	Oxidoreductase
1.1	Oxygenase
1.1.1	Monooxygenase	Alkane, steroids, fatty acid, and aromatic compounds	Incorporation of oxygen atom to substrate and utilize substrate as reducing agent. Desulfurization, dehalogenation, denitrification, ammonification, and hydroxylation of substrate	Protein engineering, bioremediation, synthetic chemistry, and so forth.
1.1.2	Dioxygenase	Aromatic compounds	Introduction of two oxygen atom to the substrate results in intradiol cleaving and extradiol cleaving with the formation of aliphatic product	Synthetic chemistry, pharmaceutical industry, bioremediation, and so forth.
1.2	Laccase	Ortho and paradiphenols, aminophenols, polyphenols, polyamines, lignins, and aryldiamines	Oxidation, decarboxylation and demethylation of substrate.	Food industry, paper and pulp industry, textile industry, nanotechnology, synthetic chemistry, bioremediation, cosmetics, and so forth.
1.3	Peroxidase
1.3.1	Lignin peroxidase	Halogenated phenolic compounds, polycyclic aromatic compounds and other aromatic compounds	Oxidation of substrate in the presence of cosubstrate H2O2 and mediator like veratryl alcohol.	Food industry, paper and pulp industry, textile industry, pharmaceutical industry, bioremediation, and so forth.
1.3.2	Manganese peroxidase	Lignin and other phenolic compounds	In the presence of Mn²^+ and H2O2 the co-substrate catalyses oxidation of Mn²^+ to Mn³^+ which results in an Mn³^+ chelateoxalate, which in turn oxidizes the phenolic substrates.	Food industry, Paper and pulp industry, textile industry, pharmaceutical industry, bioremediation, and so forth.
1.3.3	Versatile peroxidase	Methoxybenzenes and phenolic aromatic	The enzyme catalyzes the electron transfer from an oxidizable substrate, with the formation and reduction of compound I and compound II intermediates.	Industrial biocatalyst, bioremediation, and so forth.
2	Hydrolase
2.1	Lipase	Organic pollutants such as oil spill	The hydrolysis of triacylglycerols to glycerols and free-fatty acids	Control of oil spills, detergent production, baking industry, paper and pulp industry, personal care products, and so forth.
2.2	Cellulase	Cellulosic substance	Hydrolyses the substrate to simple carbohydrates.	Textile manufacturing. detergent production, paper and pulp industry, bioremediation, and so forth.
2.3	Protease	Proteins	Enzymes that hydrolyze peptide bonds in aqueous environment.	Leather, laundry, biocatalyst, bioremediation, and so forth.