Discharge of synthetic dye effluents from industries into inland and coastal waters is a global environmental problem. Hence, intensive research has been focused on decolourization of wastewater by environmentally friendly biological treatments. Bacterial laccases are currently gaining increasing attention for their potential in dye decolourization and bioremediation. In this study, process parameters were optimized to achieve efficient decolourization of a selected azo dye, methyl orange, using crude thermotolerant laccase from Acinetobacter lwoffii. Optimum decolourization of azo dye was obtained at pH 4.0 and 50°C with crude laccase from A. lwoffii after 1 h of incubation. Agitation speed for maximum decolourization was 190 rpm and 100% decolourization of methyl orange was achieved in the presence of Cu2+ while 80% decolourization was obtained in the presence of Fe2+ and Ca2+, respectively. Results show that crude laccase from A. lwoffii is efficient for dye decolourization under optimized conditions with potentials for application in the treatment of textile effluents and other dye-containing wastewater.
Keywords: Acinetobacter lwoffii, Laccase, Azo dye, Methyl orange, Decolourization.