A new Brevibacillus laterosporus L77 isolate capable of rapid decolorization and detoxification of textile azo dyes

Synthetic dyes are widely used in the textile industry and constitute one of the main environmental pollutants worldwide. In the present study, 60 bacterial isolates were analyzed for decolorization capabilities against reactive azo dye. In this screening, one has emerged as the most promising strain to degrade the selected dye, which was identified as Brevibacillus laterosporus. The effect of different physical-chemical and temporal parameters (dye concentration, temperature, pH, shaking, and kinetics) on its decolorizing potential was assessed. B. laterosporus showed decolorization efficiency higher than 90% for high concentrations of dye mixture. The best decolorizing potential was found in the range of 30-40°C and 8-9.5 pH. Agitation had negative effects on decolorization performance, with decrease in bacterial dye degradation. Decolorization higher than 90% was found in the first 12 hours of culture. UV-Vis analyses suggested the cleavage of azo bonds, since the peaks observed in untreated dye mixture reached close to zero after 12 hours of treatment. The toxicity test showed that the treatment with the bacterium was efficient in removing the toxicity of the dye mixture. These findings suggest that B. laterosporus L77 is a promising strain to be used in bioremediation of textile effluents containing azo dyes.