immobilization of organophosphorus hydrolase on the surface of bacillus subtilis spores by the adsorption method

objective: organophosphorus (ops) compounds are widely used in many pesticides, insecticides and chemical nerve agents. these compounds are hazardous for humans and the environment. organophosphate hydrolase (oph) is a homodimeric protein initially isolated from pseudomonas diminuta mg and flavobacterium species. this enzyme is able to degrade a broad spectrum of toxic ops compounds. using immobilized oph commonly presents a variety of advantages versus the free form of the enzyme. advantages include an increase in stability, cost reduction by simple recovery and reutilization of the enzyme, quick and easy separation of the reactant and product in the reaction medium. methods: plasmid pet-26b (+) was used to generate the oph protein under the control of the t7lac promoter. e. coli bl21 (de3) plyss was used as the host for expression of the oph enzyme. recombinant oph was secreted into the extracellular medium and the purified enzyme was immobilized on the surface of bacillus subtilis spores by the adsorption method, for the first time. results: approximately 42% to 45% enzymatic activity was determined to be associated with spores. optimal ph and temperature of the enzyme were not altered by the presence of the spores. thermo and ph stabilities of the immobilized enzyme was higher than the free form of the enzyme. conclusion: bacillus subtilis spores are safe for humans and the environment. therefore this system can be considered an environmentally friendly biocatalyst for degradation of ops.