Process for producing tagatose through bio-enzymatic method

Abstract

The invention discloses a process for producing tagatose through a bio-enzymatic method. The process comprises the following steps of: (1) establishing an engineering bacteria-escherichia coli BL21 (pET-15b / AI) of isomeric enzyme of L-arabinose; (2) fermenting the established engineering bacteria to obtain an L-AI-containing cell; (3) separating and purifying the L-AI; (4) catalyzing and converting D-galactose to produce D-tagatose by using the L-AI; and (5) selecting microorganisms which can metabolize D-galactose and cannot metabolize the D-tagatose to remove the D-galactose through metabolism, and purifying to obtain the D-tagatose. In the invention, the escherichia coli engineering bacteria which can effectively express the L-AI are established through a gene engineering technology, so that the L-AI can be massively expressed to supplement the insufficiency in lower efficiency of converting to produce the D-tagatose through the enzymatic catalysis of the D-galactose; and the microorganisms which can metabolize the D-galactose and cannot metabolize the D-tagatose are selected to remove substrate galactose remained after the enzyme catalytic reaction, so that the high-purity D-tagatose is obtained, thus the process has a high market application value.

Description

technical field [0001] The invention relates to a method for producing tagatose, in particular to a method for producing tagatose by utilizing a biological enzyme method. Background technique [0002] Tagatose is an isomer of D-fructose, which is rare in nature. It has been found to have special health care functions in recent years. Its sweetness is 92% of that of sucrose, and its calorific value is only 1.5Kcal / g (sucrose is 4Kcal / g). It can improve intestinal flora, lower blood sugar, resist dental caries, etc. After more than ten years of animal and human experiments, from 2001 to 2005, it was recognized as a safe food in the United States, South Korea, Australia, the World Health Organization, and the European Union, and there is no need for any restrictions on its use. Subsequently, D-tagatose is widely used in health drinks, yogurt, fruit juice and other products as a substitute for sucrose. Because D-tagatose causes very low blood sugar and insulin response, which ...

AI Technical Summary

Problems solved by technology

[0004] In the process of L-arabinose isomerase catalyzing the one-step reaction of D-galactose to produce D-tagatose, the first problem is the enzyme itself: the catalytic efficiency is low, and Kcat is in the range of 2-20s-1; The Km value of D-galactose is very high; the optimum pH for most AIs catalytic reactions is relatively high

It has been reported in the literature that Ca ion-type cation exchange resin column chromatography can be used to separate the two, but the degree of separation is low. In addition, the operation process requires a higher temperature (70 ° C), the column is unstable, and the operation is complicated.

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