Applicability of enzymes produced from different biotic species for biodegradation of textile dyes

Abstract

The industrial wastewater contains a large amount of toxic pollutants that cause severe biotic risk and deterioration of environmental quality when discharged untreated/partially treated. Among the industrial sectors, the colourant industry-produced wastewater has more complex and hazardous composition in terms of toxicity of pollutants. In the recent past, numerous bioremediation techniques based on whole cells (bacteria, fungi and plants) or enzymes have been investigated for the treatment of dye-contaminated wastewater. The enzyme-driven treatment system has been found to be an effective for achieving satisfactory decolourization of dye-contaminated wastewater in less time, cost, labour and ecological risk. The enzyme-mediated decolourization of dye occurs through either degradation or biotransformation mechanism under optimal environmental conditions. The enzyme activity is limited by the operational factors such as reactivity of dye, pH, temperature, co-substrate and electron donor. In this regard, the present paper reviews the potential of enzymes, extracted from different biota (such as bacteria, fungi, algae and plants), to decolourize dyes from contaminated wastewater. It has been observed that the enzyme activity varies with the class of enzyme, its source and targeted substrate. The enzymes belonging to the class oxidoreductase are chief biological agents involved in bioremediation of textile dyes. The peroxidase enzymes are found to be very effective against wide classes of industrial dyes, with more tolerability to high temperature ~ 60 °C and wide range of operational pH 3–11. These enzymes are easily available as it can be extracted from bacteria, fungi, algae and plants. It has been observed that the dye decolourization efficiency of enzymes is higher in an immobilized state than in soluble form.