Covalent immobilization of organophosphorus hydrolase enzyme on chemically modified cellulose microfibers: Statistical optimization and characterization

Organophosphorus hydrolase (OPH) from Flavobacterium ATCC 27551 was covalently immobilized on epoxy modified plant cellulose powder. The Taguchi method was applied to optimize the conditions of cellulose activation and binding of the OPH to the carrier surface. The chemical modification of cellulose by covalent coupling with 1, 4-butanediol diglycidyl ether was demonstrated using the FTIR technique. TEM analysis proved good linkage of the OPH over the support surface. At the identified optimum condition of affecting parameters, the activity yield of immobilized OPH on the modified cellulose was found to be 68.32%. The kinetic parameters, Km and Vmax values, were calculated and it was determined that the catalytic efficiency of the immobilized OPH was about 4.85-fold lower than that of free enzyme. The storage, thermal, and pH stabilities of the immobilized OPH were improved compared with free counterpart. The results revealed that after incubation for 24 h at 55 °C, the soluble and immobilized OPH retained 8% and 35% of their initial activities, respectively. Furthermore, the immobilized OPH showed a 59% residual activity when used ten times repeatedly. Therefore, plant cellulose as a low-cost carrier has shown excellent properties for enzyme immobilization to be used as biocatalytic material in large scale applications.