Biodegradation of Bis-Azo Dye Reactive Black 5 by White-Rot Fungus Trametes gibbosa sp. WRF 3 and Its Metabolite Characterization

Abstract

The culture ofTrametes gibbosasp. white-rot fungi (WRF) 3 under mesophilic conditions can lead to the degradation of azo dye compounds. This ability of T. gibbosa sp. WRF 3 is attributed to the released enzymes that are able to catalyze the structural degrada- tion of the azo dye compound. The effect of environ- mental factors such as carbon sources, nitrogen sources, and pH of growth medium were investigated in this research.Theadditionof20g/L glucose(carbonsource) and yeast extract (nitrogen source) at pH 5 of growth medium enhanced the decolorization of Reactive Black 5 (RB5) dye up to 87.07 % within 30 days ofincubation. The decolorization of RB5 can be analyzed using UV- vis spectroscopy and differential pulse cathodic strip- ping voltammetry (DPCSV). The maximum absorbance of RB5 was at 597 nm and decreased after the dye was treated with T. gibbosa sp. WRF 3. In the voltammetric analysis, we examined the effect of pH of Britton- Robinson buffer (BRB) medium on the detection of bis-azo compound of RB5. A stock solution of RB5 was used in the study, and it showed two reduction peak potentials at �0.5 and �0.7 V which attributed to the bis-azo bond, whereas the metabolic product showed one reduction peak at �0.6 V. The GC-MS mass spec- trum confirmed the formation of metabolites at tR 4.63 min and m/z of 73 after 30 days of incubation which was sec-butylamine.