A whole-cell catalytic method for preparing tagatose

Abstract

The invention discloses a method for preparing tagatose by using whole-cell catalysis. The method comprises the following steps of transferring plasmid containing an alpha-glucan phosphorylase gene (or cellulosic polysaccharide phosphorylase and cellobiose phosphorylase genes, or a sucrose phosphorylase gene), a phosphoglucomutase gene, a glucose phosphate isomerase gene, a 6-phosphate tagatose epimerase gene, and a 6-phosphate tagatose phosphatase gene into engineered escherichia coli, so as to obtain converted bacterial strain; inducing the converted bacterial strain to produce enzyme, and permeabilizing; mixing the permeabilized bacterial strain, establishing a whole-cell enzyme catalysis reaction system with starch or starch derivative (or mixture of cellulase and cellulose or cellulose derivative, or sugarcane), and performing the whole-cell enzyme catalysis reaction, so as to obtain the tagatose. The method has the advantages that the tagatose is prepared by the whole-cell catalysis; the cost is low, the pollution is low, the yield rate is high, and the like; the method is suitable for preparing the tagatose in a scale way.

Description

technical field [0001] The invention relates to a method for preparing tagatose, in particular to a method for preparing tagatose by catalyzing whole cells, and belongs to the field of tagatose preparation. Background technique [0002] Tagatose (D-Tagatose) is a rare monosaccharide that occurs naturally, it is the ketose form of galactose, and the epimer of fructose. The sweetness properties are similar to sucrose, and the calories produced are only one-third of sucrose, so it is called a low-calorie sweetener. Tagatose has excellent nutritional properties such as low calorie value, zero glycemic index, blood sugar passivation, no caries, prebiotic effect and antioxidant activity. Natural tagatose is mainly found in dairy products such as yogurt and milk powder. Tagatose has four major functions: low energy, lowering blood sugar, improving intestinal flora and anti-caries (Oh D-K: Tagatose: properties, applications, and biotechnological processes. App. Microbiol. Biotechn...

AI Technical Summary

Problems solved by technology

At present, the method of biotransformation to produce tagatose that has been studied more is to use L-arabinose isomerase to catalyze the conversion of D-galactose into tagatose. However, the higher price of galactose affects the final price of tagatose, resulting in Cannot be widely used (Rhimi M, Aghajari N, Juy M, Chouayekh H, Maguin E, Haser R, Bejar S: Rational design of Bacillus stearothermophilus US100l-arabinose isomerase: Potential applications for d-tagatose production.Biochim.2009,91:650 -653. OhH-J, Kim H-J, Oh D-K:Increase in d-tagatose Production Rate by Site-directedMutagenesis of l-arabinose Isomerase from Geobacillus thermodenitrificans.Biotechnol.Lett.2006,28:145-149.Bosshart A,Hee CS , Bechtold M, Schirmer T, Panke S:Directed Divergent Evolution of a Thermostable D-Tagatose Epimerase towards Improved Activity for Two Hexose Substrates.ChemBioChem 2015,16:592-601.MenY,Zhu Y,Zhang L,Kang Z,Izumori K,Sun Y, Ma Y: Enzymatic conversion of D-galactose to D-tagatose: Cloning, overexpression and characterization of l-arabinose isomerase from Pediococcus pentosaceus PC-5.Microbiol.Res.2014,169:171-178.)

[0004] Korean scientists invented a multi-enzyme-catalyzed method to convert fructose into tagatose, including using 6-phosphate tagatose epimerase and 6-phosphate tagatose phosphatase to convert fructose into tagatose (Oh DK , HONG SH, Lee SH: Aldolase, aldolase mutants and tagatose using the same production methods and compositions for production.WO 2015016544A1.Google Patents; 2015.), but this method is to produce 6-phosphate fructose from fructose, so ATP is needed to carry out fructose Substrate phosphorylation, resulting in high production cost of tagatose, not suitable for large-scale production

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