Dye Decolorization by Immobilized Recombinant rDyP and Turnover Capacity of rDyP

For an efficient application of the soluble recombinant enzyme of rDyP, immobilization of the enzyme was caried out to enhance and stabilize catalytic efficiency of rDyP. Although several conventional immobilization methods have been attempted for rDyP, no methods have been successful. Therefore, new catalysts developed for exhaust gas removal were employed. They were silica-based mesocellular foams and two silica-based porous materials, FSM-16 and AISBA-15, which were chemically synthesized. Immobilization of rDyP on them was carried out and immobilization efficiency was assessed. The overall efficiency was defined as adsorption efficiency x activity efficiency to find the maximum efficiency. The efficiency of rDyP immobilized on FSM-16 and AISBA-15 was maximum at pH 5 and pH 4, respectively. FSM-16 showed advantages over AISBA-15 in terms of stronger affinity for rDyP due to its anionic surface and much lower leaching of rDyP from FSM-16. When the rDyP immobilized on FSM-16, an anthraquinone dye, RBBR, was decolorized in repeated-batch mode, and eight sequential batches were possible, while rDyP immobilized on AISBA-15 enabled only two batches.

For evaluation of the practical potential of rDyP, the turnover capacity of rDyP was introduced. In order to minimize H2O2 inactivation for rDyP activity, four H2O2 supply methods were attempted and the turnover capacity of each method was compared. The continuous fed-batch supply of H2O2 and the stepwise fed-batch supply of the dye gave the maximum turnover capacity of 20.4. At this turnover capacity, one liter of crude rDyP solution containing 5,000 U could decolorize up to 102 g dye in 10h.

Keywords: AISBA-15, Adsorption, FSM-16, Immobilization, Inactivation by H2O2 , Leaching, Mesoporous materials, Overall efficiency, Remazol Brilliant Blue R, Recombinant DyP, rDyP, Turnover capacity.