• Applied Biological Chemistry
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• v.46 no.4
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• pp.299-304
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• 2003

A strain YB-9 was isolated from soil as a producer of the extracellular ${\beta}-D-galactosidase$, which catalyzes the hydrolysis of lactose. The strain YB-9 was identified as Streptomyces sp. on the basis of its cultural, morphological and physiological properties. After treating culture supematant of the isolate with ammonium sulfate $(15{\sim}70%)$, the precipitated protein was used as a crude ${\beta}-galactosidase$ for analyzing its reaction properties with $para-nitrophenyl-{\beta}-D-galactoside$ $(pNP-{\beta}Gal)$ and lactose as substrates. The {\beta}-galactosidase showed its maximal activity at pH $6.0{\sim}6.5$ and $60^{\circ}C$. The hydrolyzing activity of ${\beta}-galactosidase$ for both $pNP-{\beta}Gal$ and lactose was decreased by galactose. Its hydrolyzing activity for lactose was slightly decreased by glucose, but the activity for $pNP-{\beta}Gal$ was increased to 1.3-folds by glucose. Especially, its hydrolyzing activity was not affected for lactose and was increased to 1.6-folds for $pNP-{\beta}Gal$ by xylose.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 1998.07a
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• pp.36-38
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• 1998

생쥐 자궁의 조직세포는 생식주기와 초기 임신시기동안 $\beta$ -galactosidase mRNA를 지속적으로 발현하며, 이로부터 합성 및 분비되는 $\beta$ -galactosidase 단백질의 발현과 활성은 자궁의 조직추출액에서는 생식주기 중 proestrus시기에, 자궁내액에서는 diestrus시기에 가장 높게 나타났고 임신 1일째부터 4일째의 기간동안에는 임신이 진행될수록 점점 더 높게 나타났다. 이러한 결과로 미루어 $\beta$ -galactosidase는 생쥐의 생식 활동 즉, 생식 주기동안의 자궁 조직세포의 분화와 임신 초기 배아의 자궁 내막에의 착상에서 중요한 역할을 하는 것으로 사료된다.

• Applied Biological Chemistry
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• v.41 no.7
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• pp.500-504
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• 1998

The enzymatic transgalactosylation of L-ascorbic acid was investigated to synthesize a chemically stable form of L-ascorbic acid by using commercially available ${\beta}-galactosidases$. Among various enzymes examined, Aspergillus oryzae ${\beta}-galactosidase$ was found to be formed the derivative of ascorbic acid in a high yield from ascorbic acid and lactose. The reaction product was isolated by ion exchange chromatography on a $Dowex\;1\;{\times}\;8$ (Cl - form) resin and Toyopearl HW-40S gel chromatography. The product was identified as $6-O-{\beta}-_D-galactopyranosyl-_L-ascorbic\;acid$ on the basis of various experimental results, viz., UV, IR, $^1H-NMR,\;^{13}C-NMR$ and mass spectral data.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.5
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• pp.844-850
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• 1997

$\alpha$-Galactosidase was partially purified from the culture filtrate of pichia guilliermondii by Mannobiose-Sepharose affinity column chromatography. The galactosidase exhibited maximum activity at pH 4.5 and 4$0^{\circ}C$, and was stable in the pH and temperature ranges of 4 to 5.5 and 30 to 6$0^{\circ}C$, respectively. The enzyme was inhibited by $Hg^{2+}$ and $Ag^{2+}$. The enzyme activity was ot affected considerably by treatment with other metal compounds. The enzyme hydrolyzed melibiose to galactose and glucose, raffinose to galactose and sucrose, and $Gal^{3}Man_{3}(6^{3}-$\alpha$-galactosyl-1,4-mannotriose)$ to galactose and mannotriose. On the contrary, it could not hydrolyze $Gal^{3}Man_{4}(6^{3}-galactosyl-1,4-$\alpha$-mannotetraose)$.

• Journal of Applied Biological Chemistry
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• v.44 no.2
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• pp.53-58
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• 2001

Glycosidase activities in the grape flesh (Marguerite) were assayed, and the order of activity was marked as follows: ${\alpha}$-D-galactosidase>${\alpha}$-D-mannosidase>${\alpha}$-D-glucosidase>${\beta}$-D-galactosidase>${\beta}$-D-glucosidase. Of these glycosidases, ${\alpha}$- and ${\beta}$-D-galactosidases were prominently expressed by the treatment of gibberellic acid, resulting in 56 and 238% increase of activity, respectively. Most of ${\alpha}$-D-galactosidase was found in the flesh texture, and the activity increase by gibberellic acid occurred mostly in this tissue. The increase in ${\alpha}$-D-galactosidase activity was dependent on the concentration of gibberellic acid treated, showing a positive correlation. Gibberellic acid affected the content of total protein in the grape flesh, 49% increase by 75 ppm treatment. Above this concentration, higher gibberellic acid level did not influence the protein expression. Specific activity of the ${\alpha}$-D-galactosidase still increased, showing 24% increase in activity. Grape flesh subjected by gibberellic acid (100 ppm) resulted in the increased activity against a natural substrate, stachyose, showing 55% increase in activity from the grapes treated with 100 ppm of gibberellic acid. Other natural substrates, such as melibiose and raffinose, were also considerably hydrolyzed, and the extent was similar to that of stachyose hydrolysis. During postharvest storage, ${\alpha}$-D-galactosidase activity in the grape flesh increased by 51% after 20 days and then declined slowly.

• Microbiology and Biotechnology Letters
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• v.17 no.5
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• pp.524-528
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• 1989

A $\beta$-Galactosidase producing strain, Alkalophilic Bacillus sp, YS-309, has been isolated from soil sample. The strain was capable of producing large amount of intracellular $\beta$-galactosidase in the alkaline media rather than in the neutral media. The preferable medium composition has been determined to be as follows: 0.5% lactose, 0.5% yeast extract, 0.5% soybean meal, 0.1% KH$_2$PO$_4$, 0.02% MgSO$_4$7$H_2O$ 0,0.6% Na$_2$CO$_3$ (pH 9.9). The enzyme was produced by lactose or IPTG as in-ducer. But both Enzyme synthesis and cellular growth were decreased when lactose was added at the higher concentrations than 1.5% (v/v).

• Korean Journal of Food Science and Technology
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• v.22 no.2
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• pp.134-139
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• 1990

A strain of Nuruk yeast No. IS (NY-15) which produced high activity of ${\beta}-galactosidase$ was isolated from Nuruk, and the crude enzyme was prepared by whey permeate culture of the microorganism. The crude enzyme was purified 40-fold with a 7.7% yield by acetone and ammonium sulfate fractionational precipitation, and chromatography on DEAE-cellulose, DEAE-Sephadex A-50 and Agarose-PAPT. Purified ${\beta}-galactosidase$ from Nuruk yeast showed two types of subunit patterns; a slow moving band and a fast moving deeply stained band, both anode·migrating at pH 7.5. The molecular weight of the former was estimated to be about 130,000 and that of the latter was 96,000 by SDS-polyacrylamide gel electrophoresis. The optimum pH of the enzyme activity was 7.5 and maximum activity appeared at $40^{\circ}C$.

• Korean Journal of Microbiology
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• v.23 no.1
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• pp.20-24
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• 1985

The effects of various nitrogen soruces on the expression of nif gene were investigated using nif-lac fusants of Klebsiella pneumoniae. K. pneumoniae UK 2979 was infected with Mudl lysate prepared by heat induction of K. pneumoniae UK 4482. About 80 nif-lac fusants were isolated and designated as LX series. In the prescence of $NH_4^+,\;{\beta}-galactosidase$ activities on nif-lac fusants were greatly repressed. Amino acids, such as serine, glutamine and asparagine, were found to support the growth of K. pneumoniae M5al quite well, and showed a repressive effect on ${\beta}-galactosidase$ activities of nif-lac fusants LX-9 and LX-22 in NFHM. Glutamic acid, histidine and arginine rendered poor growth but high activities of ${\beta}-galactosidase$. Good cell growth and high enzyme activity were observed when complex nitrogen sources, such as casitone, proteose pepone, were employed. ${\beta}-galactosidase$ activities of LX-9 and LX-22 in nitrogen free minimal medium increased sharply within first 4 hours.

• Microbiology and Biotechnology Letters
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• v.27 no.3
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• pp.260-265
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• 1999

The structural $\beta$-galactosidase gene (lacZ) from Lactococcus lactis ssp. lactis 7962 was cloned into plamid vector pKF18, which was designated as pKF-gal. Expression of the lacZ from L. lactis 7962 was found to be higher when cells were grown at 3$0^{\circ}C$ than 37$^{\circ}C$. Maximum $\beta$-galactosidase activity was obtained when E. coli/pKF-gal was cultivated for 6hr at 3$0^{\circ}C$ and for 3hr at 37$^{\circ}C$, and L. lactis 7962 was grown for 8hr at 3$0^{\circ}C$. Enzyme induction was achieved by the addition of lactose, galactose, or lactose+IPTG to growing culture. The addition of glucose had no effect on enzyme induction.

• Microbiology and Biotechnology Letters
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• v.26 no.1
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• pp.40-44
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• 1998

A Penicillium strain which produces $eta$-galactosidase with high transgalactosylation activity, was isolated from soil and registered as Penicillium sp, KFCC 10888. When $eta$-galactosidase from Penicillium sp. KFCC 10855 reacted with 40% lactose, transgalactosylation ratio reached up to 70% at the 73% conversion of initial lactose. The biosynthesis of the enzyme in Penicillium sp. KFCC 10888 was not induced by lactose. The soybean meal was an effective component of the culture medium. The optimum pH and temperature for transgalactosylation were 4.0 and 55$^{\circ}C$, respectively. The production of galactooligosaccharides was in proportion to the initial lactose concentration. When the enzyme reacted with 40% lactose (pH 4.0) at 55$^{\circ}C$, the concentration of galactooligosaccharides increased up to 40% of total solid concentration.