Mixed azo dyes degradation by an intracellular azoreductase enzyme from alkaliphilic Bacillus subtilis: a molecular docking study

• Published in: Archives of microbiology Vol. 203; no. 6; pp. 3033 - 3044
• Main Authors: Krithika, A., Gayathri, K. Veena, Kumar, D. Thirumal, Doss, C. George Priya
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.08.2021; Springer Nature B.V
• Subjects: Acute toxicity; Azo dyes; Azoreductase; Bacillus subtilis; Biochemistry; Biodegradation; Biomedical and Life Sciences; Biotechnology; Cell Biology; Color removal; Decoloring; Decolorization; Degradation; Dyes; Ecology; Enzymes; Intracellular; Life Sciences; Metabolites; Microbial Ecology; Microbiology; Molecular docking; Original Paper; Soil contamination; Soil microorganisms; Soil pollution; Strains (organisms); Textile industry wastes; Textile industry wastewaters; Toxicity; Azo dye; Molecular docking; Azoreductase; GC–MS analysis; Bacillus subtilis
• ISSN: 0302-8933; 1432-072X
• DOI: 10.1007/s00203-021-02299-2

The rise of pollution due to the dye industries and textile wastes are evolving rapidly every day. The dyes are used in different trade names by the textile industries. The actual chemistry of dye is vague and difficult to understand even today though we are equipped technically. The toxic effects of the dyes and the reasons behind the acute toxicity are also an undiscovered mystery; therefore, no effective measures can be employed to degrade dyes. Deploying physical or chemical methods to pre-treat the azo dyes are expensive, extremely energy-consuming, and are not environment friendly. Hence, the use of microbes for textile dye degradation will be eco-friendly and is probably a cost-effective alternative to physicochemical methods. The present study was conducted to investigate the degradation of azo dyes isolated from textile effluent contaminated soil by employing the bacterial strains for degradation. The bacterial strains could degrade the optimum concentration of mixed azo dyes (200 mg/L) with an incubation up to 5 days. The decolourization of the dyes was expressed in terms of percentage of decolourization, and was found that about 87.35% of degradation by  Bacillus subtilis  strain .  The enzyme responsible was analyzed as intracellular azoreductase involved in the degradation of mixed azo dyes. The enzymatic pathway and 1-phenyl-2–4(4-methyl phenyl)-diazene 1-oxide was observed as the major metabolite by GC–MS analysis. The in silico study determined the binding of mixed azo dye with azoreductase and hypothesized that their linking could be the main reason for the degradation of mixed azo dye.