Method for preparing beta-galactosidase and application thereof

A method for preparing of β-galactosidase, the method comprising:

• seeding Bacillus circulans into a Luria-Bertani (LB) medium for culture and activation and then into a seed tank for culture to obtain a seed culture broth;
• introducing the seed culture broth into a fermentor containing a fermentation medium and fermenting to obtain a fermentation broth of Bacillus circulans;
• and
• filtering or centrifuging the fermentation broth of Bacillus circulans to remove cells to obtain a β-galactosidase liquid,
• wherein the fermentation medium comprises lactose, galactose, phytone, corn meal, yeast extract, a phosphate salt, a carbonate salt, and water.

A method for preparing an immobilized β-galactosidase, the method comprising

• seeding Bacillus circulans into a Luria-Bertani (LB) medium for culture and activation and then into a seed tank for culture to obtain a seed culture broth;
• introducing the seed culture broth into a fermentor containing a fermentation medium and fermenting to obtain a fermentation broth of Bacillus circulans;
• filtering or centrifuging the fermentation broth of Bacillus circulans to remove cells to obtain a β-galactosidase liquid;
• and
• mixing an ion exchange resin with the β-galactosidase liquid to allow a reaction to proceed to provide the immobilized β-galactosidase,
• wherein the fermentation medium comprises lactose, galactose, phytone, corn meal, yeast extract, a phosphate salt, a carbonate salt, and water.

A method for preparing a galacto-oligosaccharide, the method comprising

• seeding Bacillus circulans into a Luria-Bertani (LB) medium for culture and activation and then into a seed tank for culture to obtain a seed culture broth;
• introducing the seed culture broth into a fermentor containing a fermentation medium and fermenting to obtain a fermentation broth of Bacillus circulans;
• filtering or centrifuging the fermentation broth of Bacillus circulans to remove cells to obtain a β-galactosidase liquid;
• mixing an ion exchange resin with the β-galactosidase liquid to allow a reaction to proceed to provide the immobilized β-galactosidase;
• and
• mixing the immobilized β-galactosidase with lactose, and reacting to obtain the galacto-oligosaccharide,
• wherein the fermentation medium comprises lactose, galactose, phytone, corn meal, yeast extract, a phosphate salt, a carbonate salt, and water.