• Microbiology and Biotechnology Letters
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• v.26 no.3
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• pp.250-256
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• 1998

D-Tagatose production from D-galactose was investigated using 35 type strains of American Culture Type Collection (ATCC) and Korean Collection for Type Cultures (KCTC) which have potential to produce D-tagatose. Enterobacter agglomerans ATCC 27987 was selected as a D-tagatose producing strain due to its short fermentation time and high production of D-tagatose. Optimization of the culture conditions for D-tagatose production by E. agglomerans ATCC 27987 was performed. Among various carbon sources, D-galactose was the most effective carbon source for D-tagatose production. As the D-galactose concentration was increased, cell growth and D-tagatose production increased. Effect of nitrogen sources on D-tagatose production was studied. Of inorganic nitrogen sources, ammonium sulfate was effective one for D-tagatose production and yeast extract was the most suitable organic nitrogen nutrient. The concentrations of inorganic compounds such as KH$_2$PO$_4$, K$_2$HPO$_4$, and MgSO$_4$$.$7H$_2$O were also optimized for D-tagatose production. The optimal medium was determined to contain D-galactose of 20 g/l, yeast extract of 5.0 g/l, (NH$_4$)$_2$SO$_4$ of 2.0 g/l, KH$_2$PO$_4$ of 5.0 g/l, K$_2$HPO of 5.0 g/l, and MgSO$_4$$.$7H$_2$O of 5 mg/l. The optimal environmental conditions in a 250-$m\ell$ flask were found to be pH of 6.0, temperature of 30$^{\circ}C$, and agitation speed of 150 rpm. D-tagatose of 0.41 g/l could be obtained in 24 h from 20 g/l D-galactose at the optimal culture condition without induction and cell concentration.

• Food Industry And Nutrition
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• v.2 no.1
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• pp.16-21
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• 1997

Microbial of enzymatical methods are suitable for production of rare monosaccharides. Using oxidation and reduction ability of Microorganisms, various rare ketoses and polyols can be produced, for example D-tagatose from galagtitol by Enterobacter agglomerans strain 221e. L-tagatose from galactitol by Klebsiella pheumonias strain 40b, L-psicose from allitol by Gluconobacter frateurii IFO 3254, D-talitol from d-tagatose by Aureobasidium pullulans strain 113B, allitol from D-psicose by Enterobacter agglomerans strain 221e and so on. We can produce various rare aldoses and ketoses using aldose isomerases, for example L-galactose from L-tagatose by D-arabnose isomerase, and L-ribose from L-ribulose by L-isomerase, and so on. D-Tagatose 3-epimerase of Pseudomonas sp. ST-24 is very useful for preparationof various rare ketoses, for example D-psicose from D-fructose, D-sorbose from D-tagatose, L-fructose, from L-psicose and so on. Using polyol dehydrogenases, aldose isomerases and D-tagatose 3-epimerase, we can design the suitable for production of a certain rare monosaccharide from a suitable substrate.

• 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.

• 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.

• 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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.3
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• pp.348-354
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• 2013

To investigate the effect of tagatose on the growth of intestinal bacteria, various species were cultivated individually on m-PYF medium containing tagatose as a carbon source. The tagatose inhibited the growth of intestinal harmful microorganisms such as Staphylococcus aureus subsp. aureus, Listeria monocytogenes, Vibrio parahaemolyticus, Salmonella Typhimurium, and Pseudomonas fluorescens. In the case of beneficial microorganisms found in the intestine, Lactobacillus casei grew effectively on m-PYF medium containing tagatose, while Lactobacillus plantarum, Lactobacillus brevis, Leuconostoc citreum, and Lactobacillus acidophilus did not. To examine the effect of tagatose on fermentation by Lactobacillus casei, yogurt was prepared with tagatose as a carbon source. The resulting acid production stimulated a remarkable growth of lactic acid bacteria in the yogurt. After fermentation for 24 hours, the viable cell count and viscosity of yogurt were above 8.49 log CFU/mL and 1,266 cps, respectively. Moreover, sensory evaluations showed that the yogurt supplemented with tagatose was as acceptable as control yogurt prepared with glucose as a carbon source. The changes in pH, titratable acidity and lactic acid bacteria in yogurt prepared with tagatose did not show any significant changes during storage for 15 days at $4^{\circ}C$.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.312-316
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• 2004

Five strains, producing bacterial thermostable L-arabinose isomerase, were isolated from Korean soil samples obtained from compost under high temperature circumstances. Among these strains, the CBG-Al showed the highest L-arabinose isomerase activity at $60^\circ{C}$ and was selected as a D-tagatose producing strain from D-galactose. This strain was identified as Geobacillus thermodenitrificans based on the 16S rRNA analysis, and biological and biochemical characteristics. The isolated strain was aerobic, rod-shaped, Gram-positive, nonmotile, and an endospore-forming bacterium. No growth was detected in culture temperature below $40^\circ{C}$. The maximum growth temperature and maximum temperature of enzyme activity were $75^\circ{C}$ and $65^\circ{C}$, respectively. In metal ion effects, $Ca^{2+}$ was the most effective enzyme activator with the reaction rate by 150%. In a 5-1 jar fermentor with 3-1 MY medium, L-arabinose isomerase activity was growth-associated and pH decreased rapidly after the initial logarithmic phase.

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