Biodecolorization and biotransformation of methylene blue using mixed cultures of brown-rot fungus Daedalea dickinsii and filamentous fungus Aspergillus oryzae : identification of metabolites and degradation pathway.

This study aimed to examine biodecolorization and biotransformation of methylene blue (MB) using mixed cultures of brown-rot fungus Daedalea dickinsii and filamentous fungus Aspergillus oryzae . In addition, the ratio of D. dickinsii and A. oryzae in mixed cultures was 1 : 1, and the sample was incubated at 30 °C for 7 days in liquid medium potato dextrose broth (PDB). The results showed that the sample had the ability to remove and transform 95.24 mg L -1 MB. In this study, mixed cultures had the highest removal percentage of 64.77%, while values of 5.94% and 36.82% were obtained for single cultures of D. dickinsii and A. oryzae , respectively. LC-TOF/MS analysis results showed that peak intensity of MB compound ( m / z 284) in each treatment chromatogram decreased compared to the control. The metabolites of decolorization by D. dickinsii were C 15 H 16 N 3 S, C 16 H 19 N 3 SO, and C 16 H 21 N 3 SO, while C 31 H 48 N 3 S + was obtained using A. oryzae . For mixed cultures, the metabolites obtained included C 26 H 37 N 2 O 3 S, C 9 H 8 N 2 O 3 S, C 28 H 38 NO 2 S, and C 27 H 27 N 5 S 2 . Based on the results, mixed cultures of D. dickinsii and A. oryzae had a high MB decolorization and could be used in the textile industry.