β-Galactosidase from Exiguobacterium acetylicum: Cloning, expression, purification and characterization

Area of Science:

• Enzymology
• Biotechnology
• Food Science

Background:

• Beta-galactosidases are crucial enzymes in carbohydrate metabolism and biotechnology.
• Accurate quantification of lactulose in processed foods is challenging due to potential interference from other sugars.

Purpose of the Study:

• To characterize the enzymatic activity of beta-galactosidase from Exiguobacterium acetylicum MF03.
• To evaluate its potential for lactulose quantification in thermally processed milk.

Main Methods:

• Expression of the beta-galactosidase gene in Escherichia coli.
• Bioinformatic analysis and kinetic assessment of the enzyme.
• Testing enzyme activity on various substrates including lactulose and lactose.

Main Results:

• The Exiguobacterium acetylicum MF03 beta-galactosidase specifically hydrolyzes lactulose and o-nitrophenyl-β-d-galactopyranoside.
• The enzyme does not hydrolyze lactose, indicating a unique substrate specificity.
• This specificity prevents glucose formation, a common issue with other beta-galactosidases.

Conclusions:

• Exiguobacterium acetylicum MF03 beta-galactosidase is a promising biocatalyst for lactulose quantification.
• Its novel substrate specificity simplifies analytical procedures for processed milk, eliminating the need for glucose removal steps.