β-Galactosidase, gene and vector, strain, product containing the enzyme, and method for converting lactose and fructose into lactulose

Abstract

The invention relates to the field of microorganisms and in particular relates to beta-galactosidase and a gene, a vector and a strain thereof, a product with the enzyme, and a method for converting lactose and fructose into lactulose. The encoded gene of beta-galactosidase has nucleotide sequences as shown in SEQ ID NO:1; after one or more of the nucleotide sequences as shown in SEQ ID NO:1 are substituted, nucleotide sequences with beta-galactosidase activity are still available; the beta-galactosidase has the enzyme activity for catalyzing conversion of lactose and fructose into lactulose.A method comprises the following steps: enabling the beta-galactosidase to contact the lactose and the fructose, and catalyzing conversion of the lactose and the fructose into the lactulose. The method is environmental-friendly, the lactose and the fructose can be efficiently converted into the lactulose, and no harmful byproduct can be generated. The gene encoded beta-galactosidase has a catalysis effect at 70 DEG C, and is relatively low in pH value requirement and good in thermal stability.

Description

technical field [0001] The present invention relates to the field of microorganisms, specifically, a gene encoding β-galactosidase, a recombinant vector containing a gene encoding β-galactosidase, a gene encoding β-galactosidase or the recombinant vector Strain of vector, β-galactosidase encoded by said gene encoding β-galactosidase, product containing said β-galactosidase, and a method for converting lactose and fructose into lactulose . Background technique [0002] Lactulose is an important functional disaccharide, which has moderate sweetness and is difficult to be digested and absorbed by the human intestine. As a drug, it is a safe and effective drug for promoting intestinal peristalsis and treating constipation. As a food additive, it is A good substitute for sweetness, suitable for use as an additive in foods with special requirements (such as foods for diabetic patients). Because of its high safety, its production and application are getting more and more attentio...

AI Technical Summary

Problems solved by technology

However, there are many problems in the production of lactulose converted by these two methods, such as high reaction cost, difficult removal of catalyst, difficult separation of by-products and harmful by-products to human body

The way of chemical catalyst and electrochemical catalysis of lactose isomerization to lactulose greatly limits the application of lactulose in medicine and food

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