• Food Science and Biotechnology
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• v.17 no.3
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• pp.655-658
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• 2008

Although arabinose isomerase (E.C. 5.3.1.4), a commercial enzyme for edible tagatose bioconversion, can be expressed in an Escherichia coli system, this expression system might leave noxious by-products in food. To develop an eligible tagatose bioconversion with food-safe system, we compared the tagatose production activity of immobilized arabinose isomerase expressed in Bacillus subtilis (a host generally recognized as safe) with that of the enzyme expressed in E. coli. A 48% increase in tagatose production (4.3 g tagatose/L at $69.4\;mg/L{\cdot}hr$) was found using the B. subtilis-expressed immobilized enzyme system, compared to the E. coli-expressed enzyme system (2.9 g tagatose/L). The increased productivity with safety of the B. subtilis-expressed arabinose isomerase suggests that it is a more eligible candidate for commercial tagatose production.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.68-75
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• 2000

D-Tagatose is a potential bulking agent in food as a non-calorific sweetener. To produce D-tagatose from cheaper resources, plasmids harboring the L-arabinose isomerase gene (araA) from Escherichia coli was constructed because L-arabinose isomerase was previously suggested as an enzyme that mediates the bioconversion of galactose to tagatose as well as that of arabinose to ribulose. In the cultures of recombinant E.coli with pTC101, which harboring araA of E.coli, tagatose was produced from galactose in 9.9 % yield. The enzyme extract of E.coli containing pTC101 also converted galactose into tagatose in 96.4 % yield. For the economic production of D-tagatose, an L-arabinose isomerase of E.coli was immobilized using covalent binding on agarose. While the free L-arabinose isomerase produced tagatose with the rate of 0.48 mg/U$.$day, the immobilized one stably converted galactose into average 7.5 g/l$.$day of tagatose during 7 days with higher productivity of 0.87 mg/U$.$day. In the scaled up immobilized enzyme system, 99.9 g/l of tagatose was produced from galactose with 20 % equilibrium in 48 hrs. The process was stably repeated additional 2 times with tagatose production of 104.1 and 103.5 g/l.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.41-41
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• 2003

• Journal of Life Science
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• v.28 no.12
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• pp.1545-1553
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• 2018

The International Society of Rare Sugars (ISRS) defines rare sugars as monosaccharides and their derivatives that rarely occur in nature. Rare sugars have recently received much attention because of their many uses including low-calorie sweeteners, bulking agents, and antioxidants, and their various applications including as immunosuppressants in allogeneic rat liver transplantation, as potential inhibitors of various glycosidases and microbial growth, in ischemia-reperfusion injury repair in the rat liver, and in segmented neutrophil production without detrimental clinical effects. Because they rarely exist in nature, the production of rare sugars has been regarded as one of the most important research areas and, generally, they are produced by chemical synthesis. However, the production of rare sugars by bioconversion using enzymes from microorganisms has been receiving increased attention as an environmentally friendly alternative production method. In particular, D-allulose, D-allose, and D-tagatose are of interest as low-calorie sweeteners in various industries. To date, D-tagatose 3-epimerase, D-psicose 3-epimerase, and D-allulose 3-epimerase have been reported as D-allulose bioconversion enzymes, and L-rhamnose isomerase, Galactose 6-phosphate isomerase, and Ribose 5-phosphate isomerase have been identified as D-allose production enzymes. Elsewhere, D-tagatose has been produced by L-arabinose isomerase from various microorganisms. In this study, we report the production of D-allulose, D-allose, and D-tagatose by microorganism enzymes.