Partial purification of the crude chitinase obtained from culture filtrate of Bacillus licheniformis was carried out by fractional precipitation with ammonium sulphate, acetone, and ethanol. Ethanol (50-75%) showed the highest recovered protein and chitinase activity. Further purification of ethanol fraction, was achieved by gel filtration chromatography on Sephadex G-100, 2 protein peaks were obtained. The second peak showed a high recovered activity and was considered as the pure chitinase enzyme. Also, properties of the purified chitinase enzyme obtained from Bacillus licheniformis cultures were studied. The results showed that the optimum enzyme and substrate concentrations were 0.4 mg enzyme/reaction mixture and 0.6 mg chitin/reaction mixture, respectively. The optimum reaction temperature was 37ºC, and the pure enzyme showed a maximum activity at a reaction pH 7.0. In addition, the activity of immobilized chitinase enzyme by adsorption on different immobilization materials was studied. Carboxymethyl cellulose showed a higher enzyme activity (1.524 U/ml) as compared to the other immobilization materials, however, it was lower than the free enzyme activity. By reusing the immobilized enzyme adsorbed on carboxymethylcellulose, the chitinase activity increased till the 3rd run and reached 1.6 U/ml, and showed a gradual decrease up to the 6th run at which the adsorbed enzyme showed the lowest enzyme activity. In conclusion, chitinase enzyme obtained from Bacillus licheniformis may be a good candidate for application in different biotechnological fields especially in bioremediation of chitin wastes, the production of protoplasts of algal cells, and bio-control of fungal phytopathogens.
Bacillus lichenifomis, chitinase, purification, immobilized enzyme
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