Effective biotransformation of Reactive Black 5 Dye Using Crude Protease from Bacillus Cereus Strain KM201428

Abstract

Effective effluent treatment is a paramount step towards conserving the dwindling clean water resources. The present study describes the use of crude protease extract from Bacillus Cereus Strain KM201428 biotransformation of azo dye Reactive Black 5 (RB5). Batch experimental results displayed over 97% decolorization efficiency with initial dye concentration of 1.0 x 10-4M. The decolorization process was highly dependent on contact time, dye concentration and pH. The optimum contact time and pH for decolorization were 120 hours and pH 9 respectively at 25˚C. Biotransformation of RB5 dye was monitored using UV-Vis spectrophotometer and formed metabolites characterized by LC–QTOF-MS. Comparison of resultant LC–QTOF-MS chromatograms after decolorization confirmed complete cleavage of RB5 dye. First order kinetic fitted well with experimental data for different RB5 dye concentrations. Lineweaver-Burk plot was used to describe the apparent relationship between the decolorization rate and the dye concentration at optimized condition with the coefficient of determination R2 =1. This study comprehensively illustrates the potential of crude protease from Bacillus Cereus Strain KM201428 as an effective and environmentally friendly bacterial isolate in biodegradation of RB5 and opens a new approach in the treatment of wastewaters contaminated with high load of azo dyes.