• Microbiology and Biotechnology Letters
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• v.27 no.4
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• pp.298-303
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• 1999

An $\alpha$-D-galactosidase ($\alpha$-D-galactoside galactohydrolase, EC 3. 2. 1. 22) from earthworm was purified by affinity chromatography using N-$\varepsilon$-aminocaproyl-$\alpha$-D-galactopyranosylamine coupled to sepharose and its properties were examined. The specific activity of the purified enzyme, tested with p-nitrophenyl-$\alpha$-D-galactopyranoside as substrate, was 314 units/mg protein, representing an 122-fold purification of the original crude extract. The final preparation obtained from by Sephadex G-25 chromatography showed a single band on SDS-polyacrylamide gel electrophoresis. The molecular weight was determined to be 48,000 by SDS-polyacrylamide gel electrophoresis. The purified galactosidase was showed maximum activity at pH 4.5 and 4$0^{\circ}C$, and was stable in the pH and temperature ranges from 4.0 to 5.5 and 30 to 5$0^{\circ}C$, respectively. The enzyme activity was inhibited by Zn2+, Hg2+ and Co2+. When the purified $\alpha$-galactosidase treated to guar gum for 6 hour, gel-promoting property was increased. It was clear that enzymatic elimination of galactose from guar gum by purified $\alpha$-galactosidase would lead to a significant increase in gelation ability.

• The Journal of Natural Sciences
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• v.5 no.2
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• pp.13-17
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• 1992

Regulation of $\beta$-galactosidase biosynthesis was studied with alkalophilic, thermophilic Bacillus sp. TA-11. Biosynthesis of the enzyme was effectively induced by lactose and some low level by isoprophyl-$\beta$-D-thiogalactopyranoside(IPTG). When 30mM glucose was added at the different intervals to the culture that had been in contact with lactose, the different levels of the enzyme synthesis were observed. So, this suggests that glucose interfered with the entry of the lactose into the cells.The glucose inhibitory effect was not relieved by adding cAMP to the culture.

• Food Science and Biotechnology
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• v.18 no.6
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• pp.1342-1350
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• 2009

This paper investigates the production and optimization of $\beta$-galactosidase enzyme using synthetic medium by Kluyveromyces lactis NRRL Y-8279 in stirred tank bioreactor. Response surface methodology was used to investigate the effects of fermentation parameters on $\beta$-galactosidase enzyme production. Maximum specific enzyme activity of 4,622.7 U/g was obtained at the optimum levels of process variables (aeration rate 2.21 vvm, agitation speed 173.4 rpm, initial sugar concentration 33.8 g/L, incubation time 24.0 hr). The optimum temperature and pH of the $\beta$-galactosidase enzyme produced under optimized conditions were $37^{\circ}C$ and pH 7.0, respectively. The enzyme was stable over a pH range of 6.0-7.5 and a temperature range of $25-37^{\circ}C$. The $K_m$ and $V_{max}$ values for O-nitrophenol-$\beta$-D-galactopyranoside (ONPG) were 1.20 mM and $1,000\;{\mu}mol/min{\cdot}mg$ protein, respectively. The response surface methodology was found to be useful in optimizing and determining the interactions among process variables in $\beta$-galactosidase enzyme production. Hence, this study fulfills the lack of using mathematical and statistical techniques in optimizing the $\beta$-galactosidase enzyme production in stirred tank bioreactor.

• Journal of Microbiology and Biotechnology
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• v.5 no.1
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• pp.6-13
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• 1995

A gene coding for the $\beta$-galactosidase (lactase) of Kluyveromyces tragilis UCD 55-55 was isolated by complementation in Escherichia coli YMC9. From the plasmid library made from Sau3A-digested chromosomal DNA, one positive clone was selected. The cloned gene for $\beta$-galactosidase was on 7.3 kilobase pair DNA fragment, and a slightly low level of $\beta$-galactosidase enzyme activity was detecied in E. coli. It was also confirmed that the cloned gene comes from K. tragilis by DNA-DNA hybridization and immunochemical blotting experiments. In order to construct a new yeast strain having the metabolic ability for lactose, the cloned gene for K. tragilis $\beta$-galactosidase was inserted in yeast vector YEp24 and YRp17, and transformed into Saccharomyces cerevisiae YNN27 and Ml-2B. The yeast transformants showed the nearly the same $\beta$-galactosidase productivity as level of K. tragilis when uninduced, but these could not utilize lactose as a sole carbon source, presumably due to the lack of lactose transport system. Nevertheless, a slightly higher ethanol productivity was achieved by these transformants than S. cerevisiae or K. tragilis, in the medium containing glucose and lactose.

• The Korean Journal of Mycology
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• v.11 no.3
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• pp.109-114
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• 1983

${\beta}-Galactosidase$ activity of Aspergillus phoenicis was studied using ONPG and lactose as substrate. It increased monotonically during the exponential growth phase and dropped rapidly at the beginning of the stationary one. It exhibited high tolerable temperature and acidic optimal pH which provides certain advantages from the industrial view point. Enzyme of ${\beta}-galactosidase$ had more subsrate affinity for ONPG than for lactose and its apparent maximum activity was also higher with the former as substrate. Activity of this enzyme depended upon the conditions of immobilization. Optimum crosslinking reaction was occurred at pH 7.2 and 0. 35 vol. % of glutaraldehyde concentration.

• The Journal of Natural Sciences
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• v.5 no.1
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• pp.47-52
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• 1992

A alkalophilic, thermophilic bacterium TA-11 which produce $\beta$-galactosidase highly was isolated from compost and identified to the genus Bacillus. $\beta$-galactosidase production was maximized when it was incubated in synthetic medium containing 1.5% lactose. 0.4% peptone, 0.4% teast ext., 0.2% $MgSO_4$ 0.05% $NH_4$Cl and 0.2% NacL(initial pH; 10.0) at $50^{\circ}C$ for 2 days in reciprocal shaker.

• The Journal of Natural Sciences
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• v.4
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• pp.59-68
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• 1991

$\beta$-Galactosidase(EC 3.2.1.23) from pathogenic Neisseria lactamica 2118 was purified by p-aminopheny1-$\beta$-D-thiogalactopyranoside agarose affinity chromatography. Then some properties of the purified $\beta$-galactosidase were investigated.$\beta$-Galactosidase form Neisseria lactamica 2118 was constitutive enzyme, not induced by lactose and IPTG. Optimal activity was observed at $35^{\circ}C$ and pH 7.5 and the enzyme was stable at the range of pH 6.0-9.0 and at temperature below $50^{\circ}C$. The enzyme activity was inhibited by cations such as $Hg^(2+)$ and $Co^(2+)$.

• Microbiology and Biotechnology Letters
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• v.13 no.3
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• pp.185-189
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• 1985

Extracellular $\beta$-galactosidase from the culture broth of L. sporogenes was purified to apparent homogeniety by procedures including ammonium sulfate fractionation, Sephadex G-200 gel filtration, DEAE-Sephadex A-50 ion exchange chromatography, and Hydroxyapatite adsorption chromatography. The purifying procedures resulted in 347-fold purification with the overall yield of 39.5％ The purified enzyme had a specific activity(using ONPG as a substrate) of about 1, 585 units per mg protein. The molecular weight of the enzyme protein was estimated to be 140, 000 by gel filtration on Sephadex G-200, and SDS-polyacrylamide gel electorphoresis showed that the enzyme consisted of two identical subunits with a molecular weight of 72, 000.

• Korean Journal of Food Science and Technology
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• v.28 no.5
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• pp.987-993
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• 1996

This study was attempted to prepare milk and soymilk containing high number of viable cells of bifidobacteria during the fermentation as well as to establish the optimum condition for bacteria growth. Activity of ${\alpha}$- and ${\beta}-galactosidase$ produced by bifidobacteria was also determined. Milk and soymilk inoculated with Bifidobacterium longum ATCC 15707 were incubated in a nitrogen-carbon dioxide atmosphere at $37^{\circ}C$ for two days. and time courses of pH, acidity, viable cells and effect of growth factors were determined. After two days, pH of milk gradually decreased from 6.81 to 4.84 and pH of soymilk changed from 7.02 to 3.89. The viable cell numbers of bifidobacteria increased constantly in soymilk, while bacterial growth in milk appeared to be delayed after storage of two days. Both of ${\alpha}$- and ${\beta}-galactosidase$ activities were detected in soymilk, but activity of ${\beta}-galactosidase$ was predominant in milk. Fucosyllactose appeared to be a good growth factor in soymilk. During the fermentation of milk, L-cysteine HCl enhanced growth of bifidobacteria at the early stage and fucosyllactose was a good growth factor in the propagations of bifidobacteria from middle stage.

• Korean Journal of Microbiology
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• v.42 no.3
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• pp.216-222
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• 2006

This study was carried out to select the lactic acid bacteria producing ${\beta}-galactosidase$ (lactase) and investigate the properties of the ${\beta}-galactosidase$. About 100 strains of lactic acid bacteria showing blue colony on the MRS agar medium containing X-gal were isolated from several kinds of Kimchi. Among them, 2 strains were selected as potential ${\beta}-galactosidase$ producers. The selected strains, ET-1 and LA-12, were identified as Lactobacillus fermentum and L. acidophilus, respectively by the analysis of 16S rDNA sequences. They showed relatively high ${\beta}-galactosidase$ activity and cellular viability. Their ${\beta}-galactosidase$ showed the highest activity at $55^{\circ}C$. And the optimum pHs of the enzymes produced by ET-1 and LA-12 were pH 5.5 and pH 7.0, respectively. They were also highly resistant to artificial gastric juice and bile. Two selected strains showed little change of viable cell number for 3 hr incubation in artificial gastric juice, and maintained the viable cell number at $10^8CFU/ml$ for 24 hr in 0.3% oxgall after incubation for 2 hours in artificial gastric juice. Based on these results, ET-1 and LA-12 are expected to be applied in dairy industry.