Efficient removal of azo-dye Orange II by fungal biomass absorption and laccase enzymatic treatment.

In this study, the exact contribution of fungal biomass and laccase in the removal of the Orange II dye from liquid culture was determined. Biomass and laccase were produced with three different carbon sources [bran flakes (BF), wheat bran (WB) and wheat flour (WF)]. The contribution of the biomass and the laccase enzyme in the removal of the Orange II dye was assessed as follows: (A) in vivo treatment with fungal biomass; in vivo treatment with fungal biomass and inhibited laccase (using 0.6 mM sodium azide); and (B) in vitro treatment with crude laccase. The results of fungal biomass production were similar for all the carbon sources evaluated, while laccase volumetric activities were different. The highest enzyme production was obtained with WB, followed by BF and WF. In the in vivo treatment with fungal biomass-laccase, dye removal was over 84% for all the carbon sources. Dye adsorption by fungal biomass varied from 1.5-2%, presenting enzymatic activities ranging from 62 to 163 U L. In the in vivo treatment with fungal biomass-inhibited laccase, the removal of the dye varied from 30 to 72%. In this case, the percentage of dye adsorption by fungal biomass was significantly increased and ranged from 18 to 53%. In the in vitro treatment with laccase, the removal ranged from 80 to 84%. The best treatment for dye removal involved the use of both fungal biomass and laccase. The carbon source for biomass and laccase production had an impact on dye removal.