Evaluation of Lacc134 Oxidoreductase of Ganoderma multistipitatum in Detoxification of Dye Wastewater under Different Nutritional Conditions

Abstract

In the present study, we investigated the effects of different carbon sources (glucose, sucrose, and maltose) on laccase production from mycelium of Ganoderma multistipitatum grown on malt extract agar plates. The preliminary screening test was performed on the guaiacol plate, where a maroon brown zone formed after laccase oxidation. A few pure mycelial discs of Ganoderma species were transferred into submerged fermentation nutrient broth. The nutrient medium of submerged fermentation at 20 g of glucose revealed the highest laccase activities (2300 U/L) than other carbon sources. The interesting results also shown by inorganic NaNO3 in the production of maximum laccase (7800 ± 1.1 U/L). The organic nitrogen inducer, namely yeast extract, exhibited 5834 U/L laccase activity and a potential source of laccase secretion. The results concluded that C and N inducers enhanced the laccase production. This production process is eco-friendly and effective in the removal of dye from water. Laccase from the cultural broth was partially purified by SDS-PAGE for molecular weight determination, while Native-PAGE confirmed the laccase band after staining with guaiacol. The Km and Vmax values of Lacc134 were 1.658 mm and 2.452 mM min−1, respectively. The Lacc134 of this study effectively removed the Remazol Brilliant Blue R (RBBR) dye (extensively used in textile industries and wastewater). For dye removal capacity, 2.0 mg, 4.0 mg, 5.0 mg, and 6.0 mg were used, from which 6.0 mg was most effective in removal (85% and 88%) dye concentration in 1st and 2nd h interval treatment, respectively. Total organic carbon (TOC) quantity after dye removal percentage in the first- and second-hour time interval was 62% and 89%, respectively, at 30 g glucose. According to the experimental finding of this study, the breakdown products catalyzed by Lacc134 are less hazardous due to lower molecular weight than the dye itself.