Immobilized preparation of cold-adapted and halotolerant Antarctic beta-galactosidase as a highly stable catalyst in lactose hydrolysis.
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.
Makowski
Krzysztof
K
Institute of Technical Biochemistry, Technical University of Lodz, Lodz, Poland. krzymak@02.pl
Białkowska
Aneta
A
Szczesna-Antczak
Mirosława
M
Kalinowska
Halina
H
Kur
Józef
J
Cieśliński
Hubert
H
Turkiewicz
Marianna
M
D000818:Animals; D000864:Antarctic Regions; D001709:Biotechnology / Q000379:methods; D002384:Catalysis; D048271:Chitosan; D003080:Cold Temperature; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006868:Hydrolysis; D007785:Lactose / Q000378:metabolism*; D008863:Microspheres; D008892:Milk / Q000737:chemistry / Q000378:metabolism; D031161:Pseudoalteromonas / Q000201:enzymology* / Q000235:genetics; D012965:Sodium Chloride / Q000494:pharmacology*; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*
D004800:Enzymes, Immobilized; D012965:Sodium Chloride; D048271:Chitosan; D001616:beta-Galactosidase; D007785:Lactose