• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.3
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• pp.215-218
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• 2000

Sialytrisaccharides based on $\beta$-galactosyldisaccharides were synthesized using $\beta$-galactosidase and trans-sialidase in one pot. Using $\beta$-galactosidase from Bacillus Ciculans and trans-sialidase from Trypanosoma cruzi simulaneously, 6mM sialyltrisaccharides composed of about 95% NeuAc$\alpha$(2,3)Gal$\beta$(1,4)GlcNAc and 5% NeuAc$\alpha$(2,3)Gal$\beta$(1,6)GlcNAc were produced from a reaction mixture containing 25mM o-nitropheny1-$\beta$-D-galsctolneuraminic acid. One beauty of this reaction was that a secondary hydrolysis of the disaccharide intermediate occurring between the activated galactopyranoside and N-acetylgucosamine was prevented. Using $\beta$-galactosidase from Escherichia cloi and the same trans-sialidase, 15mM sialyltrisaccharides composed of about 90% NeuAc$\alpha$(2,3)Gal$\beta$(1,6)GlcNac and 10% NeuAc$\alpha$(2,3)Gal$\beta$(1,4)GlcNAc were produced from a reaction misture containing 400nM galactose, 800nM N-acetylglucosylation rection between galactose and N-actylgucosamine was diminant since the disaccharide intermediate mainly resulted sreulted in the silylated product.

• 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.

• 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.

• The Korean Journal of Zoology
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• v.33 no.3
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• pp.365-372
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• 1990

For the effort to produce transgenic amphibians, a plasmid DNA sequence (cytoplasmic actin promoter-linked bacterial $\beta$-galactosidase gene) was microinjected into fertilized Xenopus eggs. It appeared that the injection of 20 nl solution containing 1-2 ng of DNA was not toxic, but over 4 ng was toxic to embryonic development. The translational product of $\beta$-gal gene ($\beta$-galactosidase) had enzyme activity in all three germ layers of the embryo. Expression of the injected $\beta$-gal genes was first detected at mid-gastrula stage, and the activity persisted up to stage 43 (feeding tadpole) with decreased level of retention. However, the level of the expression was various among the injected individuals as well as each experiment. That is, $\beta$-galactosidase activities did not appear in all cells, instead a localized distribution pattern. Although other possibilities could not be omitted, this mosaic distribution of gene expression seemed to arise from unequal partition of the injected DNA into each blastomere during early cleavage.

• 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.23 no.5
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• pp.513-518
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• 1995

To evaluate bile salt-tolerance of lactic acid bacteria (LAB, Lactobacillus acidophilus ATCC 4356, Lactobacillus casei IFO 3533, Streptococcus thermnophilus KCTC 2185, Lactobacillus lactis ATCC 4797, and Lactobacillus bulgaricus ATCC 11842), We investigated the survivals, acid production and $\beta $-galactosidase activity of LAB under anaerobic broth system. Cellular permeability of LAB and their cellular retention of $\beta $-galactosidase were also examined in the same system. Although the growth of LAB was slightly suppressed by 0.3% bile salt, they showed normal growth curve. Streptococcus thermophilus KCTC 2185 was significantly more resistant to bile salt than the others. The $\beta $-galactosidase activity from Streptococcus thermophilus KCTC 2185 and Lactobacillus bulgaricus ATCC 11842 and their cellular retention of $\beta $-galactosidase decreased by 0.3% bile salt. The cellular permeability of LAB in the presence of bile salt increased significantly.

• Journal of Microbiology and Biotechnology
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• v.1 no.4
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• pp.227-231
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• 1991

A gene coding for a $\beta$-galactosidase of Bacillus subtilis HP-4 was cloned in E. coli JM109 by inserting HindIII digested fragment of B. subtilis HP-4 chromosomal DNA into the site of pBR322 and selecting recombinant transformant showing blue color on X-gal plate. The recombinant plasmid, named pBG109, was found to contain the 1.4 Kbp HindIII fragment originated from B. subtilis HP-4 chromosomal DNA by Southern hybridization. The cloned gene was stably maintained and expressed in E. coli JM109 and the pBG109 encoded $\beta$-galactosidase had the same enzymatic properties as those of $\beta$-galactosidase produced by B. subtilis HP-4.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.2
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• pp.242-246
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• 1995

This paper was carried out to investigate changes in cell wall, cell wall polysaccharides, pectic substances extracted from cell wall of persimmon fruits treated with polygalacturonase and $\beta$-galactosidase in vitro. Degrading degree of cell wall treated with cell wall-degrading enzymes were higher in order polygalacturonase, polygalacturonase+$\beta$-galactosidase and $\beta$-galactosidase. Contents of soluble pectic substances in cell wall treated with cell wall-degrading enzymes showed as the same order as degrading degree of cell wall, while contents of insoluble pectin lower. Contents of versene-soluble pectin and total pectic substance were not affected by cell wall-degrading enzymes. Contents of uronic acid and hexose in soluble material isolated from cell wall treated with polygalacturonase and mixed enzyme were higher than those of untreatment and $\beta$-galactosidase treatment.

• Microbiology and Biotechnology Letters
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• v.20 no.1
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• pp.46-52
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• 1992

The optimum condition for the developement of a whey beverage from the concentrated whey was studied. Reverse osmosis system was used to obtain concentrated lactose from cheese whey. The hydrolysis degree of lactose by $\beta$-D-galactosidase was determined using HPLC (high performance liquid chromatography). The order of hydrolysis degree was 1:1, 2:l and 3:l concentrated lactose. It resulted from the concentrated salt which slightly inhibited $\beta$-D-galactosidase with constant enzyme dosage. The optimum condition for enzyme dosage was 2% in non-concentrated lactose, 3% in 2:l and 3% in 3:l concentrated lactose after 4 hours of reaction. When the 3:l concentrated lactose was used, more than 70% was hydrolyzed by 3% enzyme dosage. Furthermore the change of fermented whey by lactic acid bacteria was investigated. Based on the result of sensory test, the most favorable response was obtained at pH 4.2 and titratable acidity of 0.7% about 6 hours of fermentation at $37^{\circ}C$ with 2%: thermophilic starter.