Change in turnover capacity of crude recombinant dye-decolorizing peroxidase (rDyP) in batch and fed-batch decolorization of Remazol Brilliant Blue R

Decolorization of the representative anthraquinone dye, Remazol Brilliant Blue R (RBBR) was assessed to determine the practical potential of crude recombinant dye-decolorizing peroxidase generated by Aspergillus oryzae (rDyP) in term of turnover capacity of rDyP. The turnover capacity, defined as the milligram of RBBR decolorized per unit of rDyP inactivated over the catalytic life time of rDyP, was quantified under condition by H₂O₂ -mediated rDyP inactivation. In batch culture, equimolar batch addition of H₂O₂ and RBBR yielded complete decolorization of RBBR by rDyP, with a turnover capacity of 4.75. In stepwise fed-batch addition of H₂O₂, the turnover capacity increased to 5.76, and by increasing dye concentration, it reached 14.3. When H₂O₂ was added in continuous fed-batch to minimize rDyP inactivation and 1.6 mM dye was added in stepwise fed-batch mode, the turnover capacity increased to 20.4. At this turnover capacity, 1 l of crude rDyP solution containing 5,000 U could decolorize up to 102 g RBBR in 650 min.