Efficient Azo Dye Biodecolorization System Using Lignin-Co-Cultured White-Rot Fungus

The extensive use of azo dyes by the global textile industry induces significant environmental and human health hazards, which makes efficient remediation crucial but also challenging. Improving dye removal efficiency will benefit the development of bioremediation techniques for textile effluents. In this study, an efficient system for azo dye (Direct Red 5B, DR5B) biodecolorization is reported, which uses the white-rot fungus Ganoderma lucidum EN2 and alkali lignin. This study suggests that the decolorization of DR5B could be effectively enhanced (from 40.34% to 95.16%) within 48 h in the presence of alkali lignin. The dye adsorption test further confirmed that the alkali-lignin-enhanced decolorization of DR5B was essentially due to biodegradation rather than physical adsorption, evaluating the role of alkali lignin in the dye biodegradation system. Moreover, the gas chromatography/mass spectrometry analysis and DR5B decolorization experiments also indicated that alkali lignin carried an excellent potential for promoting dye decolorization and displayed a significant role in improving the activity of lignin-modifying enzymes. This was mainly because of the laccase–mediator system, which was established by the induced laccase activity and lignin-derived small aromatic compounds.