The present invention relates to a novel gene coding for thermostable beta-galactosidase, Bacillus subtilis, having the above gene, a novel enzyme coded by the gene and a process for the production thereof.
Beta-galactosidase is an enzyme which hydrolyzes lactose to galactose and glucose and is widely utilized in food processing, such as the production of milk with a low lactose content or the production of galactose or glucose from lactose contained in whey obtained in a large amount as a by-product in the production of cheese.
Generally, it is desired that enzymes for use in food processing be stable at an elevated temperature from the viewpoint of preventing microbial contamination. This also applies to the aforementioned enzyme.
Further, the enzyme is also utilized as a pharmaceutical to treat intolerance to lactose. In this case, good heat resistance is preferred for stability of the preparation as well.
The present invention has been made in order to achieve the above various requirements and provides a well-defined process for producing beta-galactosidase of excellent heat stability in a commercially advantageous manner.