• Transactions of the Korean hydrogen and new energy society
• /
• v.23 no.4
• /
• pp.397-403
• /
• 2012

Galactose, an isomer of glucose with an opposite hydroxyl group at the 4-carbon, is a major fermentable sugar in various promising feedstock for hydrogen production including red algal biomass. In this study, hydrogen production characteristics of galactose-glucose mixture were investigated using batch fermentation experiments with heat-treated digester sludge as inoclua. Galactose showed a hydogen yield compatible with glucose. However, more complicated metabolic steps for galactose utilization caused a slower hydrogen production rate. The existence of glucose aggravated the hydrogen production rate, which would result from the regulation of galactose-utilizing enzymes by glucose. Hydrogen produciton rate at galactose to glucose ratio of 8:2 or 6:4 was 67% of the production rate for galactose and 33% for glucose, which could need approximately 1.5 and 3 times longer hydraulic retention time than galacgtose only condition and glucose only condition, respectively, in continuous fermentation. Hydrogen production rate, Hydrogen yield, and organic acid production at galactose to glucose ratio of 8:2 or 6:4 were 0.14 mL H2/mL/hr, 0.78 mol $H_2$/mol sugar, and 11.89 g COD/L, respectively. Galactose-rich biomass could be usable for hydogen fermenation, however, the fermentation time should be allowed enough.

• Applied Biological Chemistry
• /
• v.3
• /
• pp.25-48
• /
• 1962

The polysaccharide C prepared from gum tragacanth powder (U. S. P. grade) by the precipitation method with 85% ethanol was a neutral polysaccharide, $[{\alpha}]^{30}_D-72.2$. The polysaccharide C consisted of L-rhamnose, D-xylose, L-arabinose and D-galactose in the molar ratio 2:1:17:9 (Table 1, 2, 3, ). The polysaccharide C was methylated with dimethylsulphate and 40% NaOH, and Purdies regent. The hydrolyzate of fully methlated product ($[{\alpha}]^{22}_D-102$ in chloroform, the methoxy content 40.6%) was composed of 2, 3, 5-tri-O-methyl-L-arabofuranose (I), 3,4-di-O-methyl-L-rhamnopyranose (II), 2,3-di-O-methyl-D-xylose (III), 2,3,4-tri-O-methyl-D-galactopyranose (IV), 2,4-di-O-methyl-L-arabopyranose (?), 2,4-di-O-methyl-D-galactose(VI), 2-O-methyl-D-arabinose (VII), and L-arabopyranose(VIII) (Table 4, 5, and Fig. 4). The first partial hydrolysis (A) of the polysaccharide C with 0.05N-HCl for 4.5 hours at $80-85^{\circ}C$ released only L-arabinose: the second hydrolysis (B) with 0.1N-HCl for 5 hours at $80-85^{\circ}C$, L-arabinose and D-galactose; and the third hydrolysis (C) with 0.3N-HCl at $90-95^{\circ}C$ in sealed tube, L-rhamnose, D-xylose, L-arabinose and D-galactose. From the unhydrolyzate A' were found L-rhamnose, D-xylose, L-arabinose, and D-galactose; from B' L-rhamnose, d-xylose, L-arabinose and D-galactose; and from C' D-xylose and D-galactose respectively (Table 6). The periodate consumption and formic acid production of the polysaccharide C were measured at various time intervals. After 120 hours periodat was consumed by 1.23 mole per $C_5H_8O_4$ and formic acid was produced 0.78 mole per $C_5H_8O_4$ (Table 7). Although a definite chemical structure for this polysaccharide C may not be formulated, experimental data, especially, from methylation, partial hydrolysie and determination of its molar ratio, and periodate analysis showed that the polysaccharide C is a highly branched polysaccharide and would be constructed of galactoaraban as a main chain residue and L-arabofuranose, D-galactopyranosyl $(1{\rightarrow}1)$-L-arabofuranose, D-xylopyranosyl $(1{\rightarrow}2)$-L-rhamnopyranosyl $(1{\rightarrow}1)$-L-arabofuranose, and L-rhamnopyranosyl $(1{\rightarrow}1)$-arabofuranose, and D-galactopyranosyl-$(1{\rightarrow}2)$-L-arabopyranosyl-$(1{\rightarrow}1)$-I-arabofuranose as a branch chain or end group (page 21).

• Journal of Microbiology and Biotechnology
• /
• v.3 no.3
• /
• pp.168-173
• /
• 1993

The expression kinetics of human lipocortin I (LCI), a potential anti-inflammatory agent, was studied in the shake-flask and fermenter cultures of Saccharomyces cerevisiae carrying a galactose-inducible expression system. The cell growth, expression level of LCI, and the plasmid stability were investigted under various galactose induction conditions. The expression of LCI was repressed by the presence of a very small amount of dextrose in the culture medium, but it was induced by galactose after dextrose became completely depleted. The optimal ratio of dextrose to galactose for lipocortin I production was found to be 1.0 (10 g/l dextrose and 10 g/l galactose). With optimal D/G ratio of 1.0 and the addition of galactose prior to dextrose depletion, LCI of about 100~130 mg/l was produced. LCI at a concentration of 174 mg/l was porduced in the fed-batch culture, which was nearly a twice as much of that produced in the batch culture. The plasmid stability was very high in all culture cases, and thus was considered to be not an important parameter in the expression of LCI.

• Journal of The Korean Society of Inherited Metabolic disease
• /
• v.16 no.3
• /
• pp.135-140
• /
• 2016

Purpose: Galactose is metabolized to galactose-1-phosphate by galactokinase (GALK), galactose-1-phosphate uridyltransferase (GALT) and UDP-galactose-4-epimerase (GALE), and galactosemia occurs when each enzyme is deficient. In Korea, unlike foreign countries, classic galactosemia is rare and transient galactosemia due to GALK hyperactivity is reported, but studies on frequency, clinical significance, and genetic variation are lacking. In this study, we analyzed the clinical characteristics of patients with galactosemia due to GALK hyperactivity. Methods: We investigated 85 patients who had an elevated galactose level in the neonatal screening test without deficiency of enzymes at Department of Pediatrics, Seoul & Bucheon Soonchunhyang University Hospital from January 2008 to June 2016. We investigated the level of galactose, galactose-1-phosphate, GALK and duration of galactose normalization, and analyzed the correlation between GALK elevation and galactose, galactose-1-phosphate and duration of galactose normalization. And the levels of galactose, galactose-1-phosphate, and duration of galactose normalization were compared between the galactose-free formula feeding group and non-feeding group. Results: Mean age of visit was $26.7{\pm}16.1days$. Duration of galactose normalization was $35.3{\pm}20.5days$. Mean galactose level was $18.5{\pm}7.3mg/dL$ in the neonatal screening and follow-up galactose level in serum was $2.3{\pm}5.4mg/dL$. The mean value of galactose-1-phosphate was $6.0{\pm}4.7mg/dL$ and the mean GALK level was $3.84{\pm}1.28{\mu}mol/Hr/gHb$. There was no significant correlation between GALK levels and galactose levels in the neonatal screening test (P=0.351), and we analyzed the correlation between GALK levels and follow-up galactose levels in serum, there was no significant correlation (P=0.101). There was a significant correlation between GALK levels and galactose-1-phosphate (P=0.015), and the correlation between GALK levels and duration of galactose normalization was not statistically significant (P=0.176). 49% of the patients were fed galactose-free formula, and 45% were not. Galactose and galactose-1-phosphate levels in the neonatal screening test were statistically significantly higher (P=0.004, 0.034) in using galactose-free formula group. Duration of galactose normalization was not related to the use of galactose-free formula (P=0.266, 0.249). Conclusion: Galactosemia due to GALK hyperactivity seems to be a temporary phenomenon and may not require galactose restriction. More research is needed on the role of the nuclear protein, racial traits and genetic variations in Korean patients.

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

• Journal of Mushroom
• /
• v.11 no.4
• /
• pp.187-193
• /
• 2013

A galactose fermentation bacterium producing lactose from red seaweed, which was known well to compromise the galactose as main reducing sugar, was isolated from button mushroom bed in Buyeo-Gun, Chungchugnamdo province. The lactic acid bacteria MONGB-2 was identified as Lactobacillus paracasei subsp. tolerans by analysis of 16S rRNA gene sequence. When the production of lactic acid and acetic acid by L. paracasei MONGB-2 was investigated by HPLC analysis with various carbohydrates, the strain MONGB-2 efficiently convert the glucose and galactose to lactic acid with the yield of 18.86 g/L and 18.23 g/L, respectively and the ratio of lactic acid to total organic acids was 1.0 and 0.91 g/g for both substrates. However, in the case of acetic acid fermentation, other carbohydrates besides galactose and red seaweed hydrolysate could not be totally utilized as carbon sources for acetic acid production by the strain. The lactic acid production from glucose and galactose in the fermentation time courses was gradually enhanced upto 60 h fermentation and the maximal concentration reached to be 16-18 g/L from both substrates after 48 h of fermentation. The initial concentration of glucose and galactose were completely consumed within 36 h of fermentation, of which the growth of cell also was maximum level. In addition, the bioconversion of lactic acid from the red seaweed hydrolysate by L. paracasei MONGB-2 appeared to be about 20% levels of the initial substrates concentration and this results were entirely lower than those of galactose and glucose showed about 60% of conversion. The apparent results showed that L. paracasei MONGB-2 could produce the lactic acid with glucose as well as galactose by the homofermentation through EMP pathway.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.9
• /
• pp.1193-1205
• /
• 2002

• KSBB Journal
• /
• v.15 no.2
• /
• pp.113-119
• /
• 2000

In order to produce xylitol with high yield, experiments were carried out to develope xylitol dehydrogenase (XDH) defective m mutant from Pichia stipitis and to investigate the xylit이 fermentation characteristics of mutant strain. After treatment of P s stipitis with EMS, mutant PXM-4 was selected based on the XDH activity and xylitol production capability. Among the tested c cosubstrates, galactose was selected as an adequate cosubstrate on xyl뻐I production of mutant PXM-4. With the increase of galactose concentration, xylitol production was decreased because the transport of xylose into cell was inhibited by g galactose. The optimal concentration of galactose for the production of xylitol using 20 g/L xylose was 20 g/L. Under this c condition, maximum concentration of xylitol and yield were 14.4 g/L and 97%, respectively. In order to prevent the inhibitory e effect of xylose transport by galactose, galactose was fed with low concentration and the concentration of xylitol produced w was increased up to 25 g/L. In the fermentation of corn cob hydrolyzate by mutant PXM-4, xylose was completely converted t to xylit이 with a 100% yield in 4 days culture.

• Microbiology and Biotechnology Letters
• /
• v.24 no.4
• /
• pp.493-499
• /
• 1996

Lactan gum produced by Rahnella aquatilis is a high viscous, anionic polysaccharide and has shear thinning behaviour. Lactan gum yield and cencentration was greater on disaccharide such as lactose and sucrose than on monosaccharides such as glucose and galactose. When initial carbon source concentration was 45g/l of sucrose of lactose, the microorgnisms produced 28 g/l and 27 g/l of lactan, respectively with a yield more than 60%. $\beta$-Galactosidase, hydrolyzing lactose into galactose and glucose, was induced by lactose or galactose. When initial corbon source was 45 g/l of mixed carbon I (glucose:galactose=1:1), lactan gum concentaration was higher than that from 45 g/l of monosaccharide (glucose pf galactose) but was similar to the result from 45 g/l of lactose. Therefore, lactose hydrolysis reaction by $\beta$-galactosidase does not seem to be a rate determining step in lactan gum biosynthesis. When initial carbon source was 45 g/l of mixed carbon II (glucose:fructose=1:1). total carbon source consumption rate was slower than that from sucrose, but glucose consumption rate was faster than that from fructose.

• Journal of Microbiology and Biotechnology
• /
• v.24 no.2
• /
• pp.264-269
• /
• 2014

For the production of ethanol from seaweed as the source material, thermal acid hydrolysis and enzymatic saccharification were carried out for monosugars production of 25.5 g/l galactose and 7.6 g/l glucose using Gelidium amansii. The fermentation was performed with Pichia stipitis KCTC 7228 or Saccharomyces cerevisiae KCCM 1129. When wild P. stipitis and S. cerevisiae were used, the ethanol productions of 11.2 g/l and 6.9 g/l were produced, respectively. The ethanol productions of 16.6 g/l and 14.6 g/l were produced using P. stipitis and S. cerevisiae acclimated to high concentration of galactose, respectively. The yields of ethanol fermentation increased to 0.5 and 0.44 from 0.34 and 0.21 using acclimated P. stipitis and S. cerevisiae, respectively. Therefore, acclimation of yeasts to a specific sugar such as galactose reduced the glucose-induced repression on the transport of galactose.