Fungal–bacterial synergism enhanced decolorization of reactive red 120 by response surface methodology

This study applied co-cultured fungus and bacterium shaking system with optimal medium constituents for fast and maximal decolorization of azo dye. The Aspergillus niger and Bacillus sp. were used to develop a consortium on scrub sponge, which can decolorize reactive red 120 to 90% after 24 h cultivation. Response surface methodology (RSM) was used to investigate the optimal medium composite, 0.1% malt extract and 0.7% KH2PO4, and predicted maximal decolorization achieved 92.68% for 2 h culture and experimental decolorization was 94.5% at initial 50 mg/L concentration. Residual dye was measured by UV–Vis spectrophotometer, and biodegradation metabolites were confirmed by HPLC and FTIR. We revealed a degradation pathway of reactive red 120 with release of 2-aminobenzenesulfonic acid and 3-methanesulfinylbut-3-en-2-one as final metabolite, and terminal degraded metabolites confirmed by phytotoxicity were nontoxic naturally. This study indicated the high potential of fungal–bacterial co-cultured system as an excellent technical innovation for azo dye decolorization.

► Co-cultured fungus-bacterium for fast and maximal decolorization of azo dye. ► Aspergillus niger and Bacillus sp. were developed a consortium on scrub sponge. ► Response surface methodology used to investigate the optimal medium composite. ► This study revealed a degradation pathway of reactive red 120. ► The terminal degraded metabolites confirmed by phytotoxicity were nontoxic.