• Journal of the Korean Society of Food Science and Nutrition
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• v.15 no.4
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• pp.32-39
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• 1986

A strain of Aspergillus niger CAD 1 which produces considerable amount of beta-galactosidase was selected from extracellular beta-galctaosidase producing fungi isolated from soil. Optimal conditions for the enzyme from Aspergillus niger CAD 1 were the growth in wheat bran supplemented with 0.5% skim milk powder at $30^{\circ}C$ for 72 hrs. The crude enzyme was purified 1,387 fold through DEAE-cellulosc and Sephadex G-100 chromatographr and its recovery was 6.2%, The optimal pH and temperature for the purified enzyme were pH 4.5 ana $45^{\circ}C$, respectively. The Km and Vmax on ONPG were $3.57{\times}10^3M$ and 33.0 unit/mg protein, whereas those on lacose were $83.3{\times}10^3M$and 15.33 unit/mg protein, respectively, The activation energy for the enzyme was 9,900 cal/mol and the enzyme had no metal ion requirement for its activity and stability. The hydrolysis of lactose in skim milk, 4.8% lactose solution and acidic whey were 65%, 70% and 78% after 10 hrs incubation at $45^{\circ}C$, when 182 units of the enzyme were used 50ml of the substrate solutions.

• The Korean Journal of Food And Nutrition
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• v.28 no.6
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• pp.1026-1032
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• 2015

This study attempted to find an efficient method for the preparation of high-purity galactooligosaccharides (HP-GOS) using ${\beta}$-galactosidase and yeast fermentation. GOS prepared using Lactozym 3000L showed the greatest enhancement in total GOS of the six ${\beta}$-galatosidases tested. GOS alone achieved 51% conversion of initial lactose. GOS production was enhanced by fermentation with commercial yeast (Saccharomyces cerevisiae); its concentration reached 71% after 36h fermentation with 8% yeast. Component sugar analysis with HPLC indicated that HP-GOS fermented with S. cerevisiae showed significantly increased levels of 4'/6'-galactosyllactose and total GOS as well as a significantly decreased glucose level. HP-GOS facilitated the growth of Lactobacillus sp. (L. acidophilus and L. casei) and Bifidobacterium sp. (B. longum and B. bifidum). In sum, high-purity GOS has been successfully produced through both an enzymatic process and yeast fermentation. GOS encourages the growth of bacteria such as Lactobacillus and Bifidobacterium that may be beneficial to human gastrointestinal health.

• The Korean Journal of Zoology
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• v.38 no.4
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• pp.550-556
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• 1995

The c-myc proto-oncogene is Involved In the control of normal cell proliferation and differentiation of many cell lineages. Although it has heen suggested that c-myc may play an important role in the mammalian early development, it Is unclear whether the embryonic c-myc mRNA is originated from zygotic gene expression or stored maternal message. Thus, we have construded expression vectors, In which the 5, flanking sequences including c-myc promoter region and a large non-coding exon I are fused 'sith E. coli lacZ gene that encedes $\beta$-galactosldase as a reporter. As c-myc exon I contains a modulatory sequence, we designed t, vo types of vectors (pcmyc.Gall and pcmyc-Ga12) to examine the role of exon I in c-myc expression. The former contains the complete exon I and the later has a deletion in 40 bp of modulator sequence located In the exon I of c-myc These vectors were microInjected into fertilized one-cell embryos and $\beta$-galactosidase activity was examined by X-gal staining during early embryogenesis. $\beta$-galactosidase activity derived from c-myc promoter was decreased at two-cell stage. The expression level directed by pcmyc- Ga12 was similar to that of pcmyc-Gal1, indicating that the medulatory sequence in exon I may not be Involved at least In the regulation of embryonic c-myc expression. In summary, the present study indicates that the c-myc promoter is functional at the early stage embryo, and the regulation of c-myc expression is under the control of "zygotic" clock of preimplantation mouse embryos.e embryos.

• Journal of Microbiology and Biotechnology
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• v.24 no.5
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• pp.675-682
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• 2014

Approximately 50% of people in the world experience abdominal flatulence after the intake of foods containing galactosides such as lactose or soybean oligosaccharides. The galactoside hydrolyzing enzymes of ${\alpha}$- and ${\beta}$-galactosidases have been shown to reduce the levels of galactosides in both the food matrix and the human gastrointestinal tract. This study aimed to optimize the production of ${\alpha}$- and ${\beta}$-galactosidases of Bifidobacterium longum subsp. longum RD47 with a basal medium containing whey and corn steep liquor. The activities of both enzymes were determined after culturing at $37^{\circ}C$ at pH 6.0 for 30 h. The optimal production of ${\alpha}$- and ${\beta}$-galactosidases was obtained with soybean oligosaccharides as a carbon source and proteose peptone no. 3 as a nitrogen source. The optimum pH for both ${\alpha}$- and ${\beta}$-galactosidases was 6.0. The optimum temperatures were $35^{\circ}C$ for ${\alpha}$-galactosidase and $37^{\circ}C$ for ${\beta}$-galactosidase. They showed temperature stability up to $37^{\circ}C$. At a 1 mM concentration of metal ions, $CuSO_4$ inhibited the activities of ${\alpha}$- and ${\beta}$-galactosidases by 35% and 50%, respectively. On the basis of the results obtained in this study, B. longum RD47 may be used for the production of ${\alpha}$- and ${\beta}$-galactosidases, which may reduce the levels of flatulence factors.

• Journal of Microbiology
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• v.45 no.6
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• pp.583-589
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• 2007

The promoter region of pyrC (dihydroorotase) gene of Escherichia coli was shown to have Fur protein binding properties by gel retardation assay. In vivo regulation of the pyrC expression was studied by measuring dihydroorotase activity and ${\beta}$-galactosidase level in the $fur^+$ and $fur^-$ genetic background. The expression of chromosomal dihydroorotase activity and ${\beta}$-galactosidase activity of pyrC-lacZ fusion plasmid was repressed to about 30% and 17%, respectively in the $fur^+$ strain compared to those in the $fur^-$ strain. Divalent ions such as $Fe^{2+}$ and $Zn^{2+}$ were not required for the repression. PyrC expression was also reduced to one half by 1 mM uracil. The effect of uracil was independent on the fur gene.

• Journal of Microbiology and Biotechnology
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• v.4 no.2
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• pp.151-154
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• 1994

Lactobacillus acidophilus KFRI 233, a strain isolated from human, was selected as a candidate for probiotics due to its excellent growth in MRS broth where no special anaerobic condition is required. Both simultaneous and deferred agar diffusion assays exhibited Lb. acidophilus KFRI 233 to possess an antagonistic effect against Clostridium perfringens. Its antagonistic effect was pH dependent Associative culture of KFRI 233 and Cl. perfringens in broth resulted in maximum 94.04% inhibition of Cl. perfringens. $\beta$-Galactosidase activity of KFRI 233 was higher than other tested strains that are sold as commercial probiotics. Survival of KFRI 233 in pasteurized skim milk (4$^{\circ}C$) and Sherbet mix (-15$^{\circ}C$) after 7 days of storage were 71.9 and 105.5%, respectively.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.762-766
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• 2001

The nar promoter of Escherichia coli was known to induce maximally under anaerobic or microaerobic conditions in the presence of nitrate. In this study, the nar promoter was tested to see whether the expression level of a reporter gene which fused lacZ gene at nar promoter's downstream, in the some gram negative host strains(Agrobacterium, Pseudomonas and Rhizobium). A nar promoter system(Combination of nar promoter and gram negative strain) was grown under aerobic conditions to absorbance at 600 nm of nearly 2.0 and then, the nar promoter was induced by lowering DO to 1-2% with alternating microaerobic and aerobic condition in the fermentor cultures, using different gram negative hosts. For a wild type nar promoter (pNW61), it was possible to maintain production of ${\beta}-galactosidase$ activity per cell(specific ${\beta}-galactosidase$ activity) at 14,000, 9600, 45 Miller units in the presence of 1% nitrate. and for a nitrate - independent nar promoter (pNW618) at 12,000, 10,400 and 58 Miller units in the absence of nitrate ion, respectively.

• KSBB Journal
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• v.13 no.3
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• pp.325-330
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• 1998

The methylotrophic yeast, Pichia pastoris, is known to be a potential host to offer many advantages for production of recombinant proteins. Fermentation parameters were optimized to enhance the heterologous ${\beta}$-galactosidase productivity with P. pastoris. Optimum concentration of methanol, used as inducer, was observed to be 8 g/L and the extent of repression of AOX1 promoter by glycerol was lower than by glucose. The degradation of the gene product ${\beta}$-galactosidase by protease was inhibited as the pH increased from 5 to 8 and the yeast extract(1%) as nitrogen source increased expression level 4 times higher compared to yeast nitrogen base(1%) as nitrogen source increased expression level 4 times higher compared to yeast nitrogen base(1%). Induction method, in which methanol is just added to fermentation medium without centrifugation, was found to be as much effective as the one with centrifugation.

• Korean Journal of Microbiology
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• v.28 no.2
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• pp.114-119
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• 1990

A yeast chromosomal superkiller gene (SK13) was cloned and expressed in $ski3^{-}$ Saccharomyces cerevisiae strains. The gene was fused to the structural region of E. coli lacZ gene at its C-terminus in a yeast-E. coli shuttle vector, pSR605. The fused gene complemented $ski3^{-}$ strains with SK13 activity and the quantitative level of expression was measured as determined by assaying $\beta$-galactosidase activity. The SDS-polyacrylamide gel electrophoresis and the Western blot analysis of this fused protein showed the immuno-reacted bands with a protein of the estimated molecular size (ca.250Kd).

• Asian-Australasian Journal of Animal Sciences
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• v.8 no.5
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• pp.449-454
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• 1995

The present study was conducted to assess gene expression of bacterial lacZ driven by the SV40 promoter at early developmental stages of bovine embryos. The lacZ gene was linearized with BamHI digestion and introduced into the pronucleus by microinjection at 20 hrs after the commencement of in vitro fertilization. Intact bovine blastocysts were not stained with X-Gal, suggesting that there is no endogenous beta-galactosidase activity in these blastocysts. In contrast, the bovine blastocyst cells microinjected with the lacZ gene exerted a characteristic greenish-blue color originating from the bacterial beta-galactosidase activity, albeit at a low rate, i.e. 2.1% of the total fertilized oocytes injected. It was concluded, therefore, that the lacZ gene driven by the SV40 promoter could be used for an indirect screening method in which the presence of transgene is evaluated from the product of transgene expression.