Open AccessImmobilized preparation of cold‐adapted and halotolerant Antarctic β‐galactosidase as a highly stable catalyst in lactose hydrolysis
Author(s) -
Makowski Krzysztof,
Białkowska Aneta,
SzczęsnaAntczak Mirosława,
Kalinowska Halina,
Kur Józef,
Cieśliński Hubert,
Turkiewicz Marianna
Publication year - 2007
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2006.00208.x
Subject(s) - lactose , hydrolysis , biology , halotolerance , glutaraldehyde , immobilized enzyme , beta galactosidase , enzyme , galactose , chromatography , biochemistry , escherichia coli , bacteria , chemistry , genetics , gene
A cold‐active β‐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°C higher (50 vs. 40°C, respectively), optimum pH range was wider (pH 6–9 and 6–8, respectively) and stability at 50°C was increased whilst its pH‐stability remained unchanged. Soluble and immobilized preparations of Antarctic β‐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 β‐galactosidase was maintained for at least 40 days of continuous lactose hydrolysis at 15°C and its shelf life at 4°C exceeded 12 months. Lactose content in milk was reduced by more than 90% over a temperature range of 4–30°C in continuous and batch systems employing the immobilized enzyme.