Production of Remazol Brilliant Blue R decolourising oxygenase from the culture filtrate of Funalia trogii ATCC 200800

Abstract

Decolourisation of Remazol Brilliant Blue R, an azo textile dyestuff, by crude filtrate of Funalia trogii ATCC 200800 growing in solid-state fermentation (SSF) medium containing wheat bran and soybean hull was studied. Optimum pH and temperature for laccase and horseradish like peroxidase (HRP) production in SSF medium were determined at 5 and 30 °C, respectively. Maximum enzyme synthesis was found in 10 days old cultures. We also found Remazol Brilliant Blue R decolourising enzymatic activity in the culture filtrate of F. trogii. The optimum pH and temperature for enzymatic decolourisation were determined at 3.0 and 50 °C, respectively. Both veratryl alcohol and peroxide ions (H 2O 2) accelerated the peroxidase enzyme reactions, whereas decelerated the decolourisation of RBBR with the culture filtrate of F. trogii. Sodium azide (NaN 3), cysteine and sodium cyanide (NaCN) inhibited RBBR decolourising activity, laccase and peroxidase activities. When sodium metabisulphite (Na 2S 2O 5) was used as an inhibitor, a significant inhibition of laccase and dye decolourising enzyme activities but no peroxidase activity was observed. Initial colourless and later orange bands were obtained by the activity staining process with RBBR and laccase substrate (guaicol), respectively, after separation by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The molecular mass of this band was estimated as about 65 kDa by SDS-PAGE. Since the reaction was catalysed in the absence of H 2O 2 as co-substrate, it was concluded that this enzyme was a laccase.