Immobilized preparation of cold-adapted and halotolerant Antarctic beta-galactosidase as a highly stable catalyst in lactose hydrolysis |
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Authors: | Makowski Krzysztof Białkowska Aneta Szczesna-Antczak Mirosława Kalinowska Halina Kur Józef Cieśliński Hubert Turkiewicz Marianna |
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Affiliation: | Institute of Technical Biochemistry, Technical University of Lodz, Lodz, Poland. krzymak@02.pl |
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Abstract: | A cold-active beta-galactosidase of Antarctic marine bacterium Pseudoalteromonas sp. 22b was synthesized by an Escherichia coli transformant harboring its gene and immobilized on glutaraldehyde-treated chitosan beads. Unlike the soluble enzyme the immobilized preparation was not inhibited by glucose, its apparent optimum temperature for activity was 10 degrees C higher (50 vs. 40 degrees C, respectively), optimum pH range was wider (pH 6-9 and 6-8, respectively) and stability at 50 degrees C was increased whilst its pH-stability remained unchanged. Soluble and immobilized preparations of Antarctic beta-galactosidase were active and stable in a broad range of NaCl concentrations (up to 3 M) and affected neither by calcium ions nor by galactose. The activity of immobilized beta-galactosidase was maintained for at least 40 days of continuous lactose hydrolysis at 15 degrees C and its shelf life at 4 degrees C exceeded 12 months. Lactose content in milk was reduced by more than 90% over a temperature range of 4-30 degrees C in continuous and batch systems employing the immobilized enzyme. |
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Keywords: | Antarctic β-galactosidase immobilized enzyme chitosan beads lactose hydrolysis in cold |
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