Immobilization of Bacillus licheniformis 5A1 milk-clotting enzyme and
characterization of its enzyme properties |
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Authors: | Mona A Esawy Yannick Combet-Blanc |
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Institution: | (1) Department of Chemistry of Natural and Microbial Products, National Research Center, Cairo, Dokki, Egypt;(2) Laboratoire de microbiologie IRD, IFR-BAIM, Universités de Provence et de la Méditerranée, ESIL case 925, 13288 Marseille Cedex 9, France |
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Abstract: | Milk-clotting enzyme from Bacillus licheniformis 5A1 was immobilized on Amberlite IR-120 by ionic binding. Almost all the enzyme activity was retained on the support. The
immobilized milk-clotting enzyme was repeatedly used to produce cheese in a batch reactor. The production of cheese was repeated
5 times with no loss of activity. The specific activity calculated on a bound-protein basis was slightly higher than that
of free enzyme. The free and immobilized enzyme were highly tolerant to repeated freezing and thawing. The optimum temperature
for milk-clotting activity was 70 °C with the free enzyme whereas, it was ranged from 70 to 80 °C with the immobilized milk-clotting
enzyme. The activation energy (E
A) of the immobilized milk-clotting enzyme was lower than the free enzyme (E
A = 1.59 and 1.99 Kcal mol−1 respectively). The immobilized milk-clotting enzyme exhibited great thermal stability. The milk-clotting optimum pH was 7.0
for both free and immobilized enzyme. The Michaelis constant K
m of the immobilized milk-clotting enzyme was slightly lower than the free enzyme. |
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Keywords: | Bacillus licheniformis immobilization milk-clotting enzyme |
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