Breaking the colour barrier: Role of extremophiles in azo dye degradation

Abstract

Abstract

Effluents released from textile industries are a major source of environmental pollution containing largest and most extensively used category of synthetic azo dyes that are widely utilised in multiple industries and have limitations to the conventional physico-chemical treatments. Bioremediation is green remediation approach that involves microorganisms or their enzymes to degrade and detoxify the pollutants from the environment. Extremophiles that thrive at extreme environmental conditions such as hot water springs have the efficiency to decolorise and detoxify the azo dyes textile wastewater. The quantitative analysis show that extremophiles achieve more than 85–95 % decolorisation of different azo dye in a short retention time at high temperature and pH, with higher efficiency and degradation rate than mesophiles. The mechanism includes reductive cleavage of azo bonds, followed by mineralisation and co-metabolism, with the help of extremozymes such as azoreductase, laccase and peroxidase. Enzymes are integrated with nano-materials forming a nano-biocatalytic platform that enhance dye degradation removal efficiency. The current study highlights the potential and application of extremophilic bacteria as a sustainable bioresource in the remediation of azo dyes and places them at the centre of new generation wastewater treatment.