• Korean Journal of Microbiology
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• 제22권2호
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• pp.77-84
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• 1984

This examined some conditions for the induction of ${\beta}$-D-galactosidase synthesis in Candida kefyr CBS 834. The optimal pH, temperature, and inoculum size either for growth or${\beta}$-D-galactosidase synthesis were 5.5, $30^{\circ}C$ and above 0.2 at A610nm, respectively. Enzyme activity began to increase at 2h after the addition of inducer, and continued to increase linearly up to $2{\sim}3h$ before reaching stationary phase, and thereafter its activity was decreased. ${\beta}$-D-galactosidase was induced either by lactose or galactose but not either by glucose or ethanol. The greater activity of ${\beta}$-D-galactosidase on galactose than on lactose indicated that the former might be natural inducer for ${\beta}$-D-galactosidase synthesis. The rate of its induction as a function of lactose concentration showed that enzyme activity increased linearly above 4mM, while it was very low below that. Glucose represed the induction of ${\beta}$-D-galactosidase, and the period of adaptation to inducer from other carbon sources was relatively short.

• Korean Journal of Microbiology
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• 제27권3호
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• pp.181-187
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• 1989

Plasmid DNA was isolated from Lactobacillus casei SW-M1($Lac^{+}$strain). The curing frequencies of pPLac plasmid from L. casei SW-M1 showed 43% for acriflavin treatment and 53% for ethidium bromide treatment after 3 times transfer. On the charaterization of pPLac plasmid, it was found that the plasmid contained gene encoding phospho-$\beta$-galactosidase for lactose utilization. Lactose-PTS(phosphotransferase system)was involved in membrane transport system in $Lac^{+}$ strain. Induction of phospho-$\beta$-galactosidase was specially effective by galactose, lower effect with lactose and glucose but not by IPTG(isopropyl-$\beta$-D-thiogalactoside). This result showed that induction of phospho-$\beta$-galactosidase by IPTG did not appeared. The catabolite repression of phospho-$\beta$-galactosidase synthesis by glucose was not found in L. casei.

• Journal of Microbiology and Biotechnology
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• 제16권12호
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• pp.1968-1976
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• 2006

Recombinant E. coli ACV 1003 (recA:: lacZ) was used to measure low concentrations of DNA-damaging chemicals, which produce $\beta$-galactosidase via an SOS regulon system. Very low $\beta$-galactosidase activities of less than 0.01 unit/ml, $\beta$-galactosidase produced through an SOS response corresponding to the 10 ng/ml (ppb) of DNA damaging chemicals in the environment, can be rapidly determined by using an alternative interferometric biosensor with optically flat thin films of porous silicon rather than by the conventional time-consuming Miller's enzyme assay as well as the ELISA method. fu order to enhance the sensitivity in the interferometry, it needs to obtain more uniform distribution and higher biolinking efficiency, whereas interferometric sensing is rapid, cheap, and advantageous in high throughput by using a multiple-well-type chip. In this study, pore size adjusted to 60 nm for the target enzyme $\beta$-galactosidase to be bound on both walls of a Si pore and a calyx crown derivative was apllied as a more efficient biolinker. Furthermore, anti-$\beta$-galactosidase was previously functionalized with the biolinker for the target $\beta$-galactosidase to be specifically bound. When anti-$\beta$-galactosidase was bound to the calyx-crown derivative-linked surface, the effective optical thickness was found to be three times as high as that obtained without using anti-$\beta$-galactosidase. The resolution obtained was very similar to that afforded by the time-consuming ELISA method; however, the reproducibility was still unsatisfactory, below 1 unit $\beta$-galactosidase/ml, owing to the microscopic non-uniform distribution of the pores in the etched silicon surface.

• Applied Biological Chemistry
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• 제36권3호
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• pp.191-196
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• 1993

This method using the synthesis substrate of $5-bromo-4-chloro-3-indolyl-{\alpha}-galactoside\;(X-{\alpha}-Gal)$ was examined for the differential enumeration of Bifidobacteria and lactic acid-producing bacteria. Bifidobacteria possess a high level of ${\alpha}-galactosidase$ activity. Bifidobacterium longum KCTC 3215 exhibited the highest ${\alpha}-galactosidase$ specific activity (8.57 units/mg protein). Determination of ${\alpha}-galactosidase$ activity using the PNPG procedure showed that Lactobacillus, Streptococcus, Pediococcus, and Leuconostoc strain had lower ${\alpha}-galactosidase$ activity as compared to Bifidobacteria. The $X-{\alpha}-Gal$ based medium is useful to identify Bifidobacteria among lactic acid-producing bacteria since the enzyme action of ${\alpha}-galactosidase$ spills $X-{\alpha}-Gal$ substrate and releases indol which impacts a blue color to Bifidobacterial colonies on agar plates. All strains of Bifidobacteria appeared as blue colonies on MRS agar medium supplemented with $100\;{\mu}M\;X-{\alpha}-Gal$ while colonies of other lactic acid-producing bacteria appeared white or light blue.

• Microbiology and Biotechnology Letters
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• 제9권4호
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• pp.207-212
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• 1981

A strain of Penicillium sp. which produces considerable amount of $\beta$-galactosidase was selected from extracellular $\beta$-galactosidase-producing fungi isolated from soil. The enzyme was found to be very stable in neutral pH range. Maximum enzymatic activity was reached after 72 hr of incubation in a wheat bran medium at 3$0^{\circ}C$. Productivity of the enzyme appeared not to be affected by the addition of carbon sources to the medium but the activity of the enzyme was increased from 14% to 85% by the addition of various nitrogen sources. The enzyme extracted from the wheat-bran culture of the Penicillium sp. was purified to 5050-fold by ammonium sulfate fractionation, SP-Sephadex C-50 chromatography, Ultrogel AcA 44 filtration and hydroxyapatite chromatography. The purified $\beta$-galactosidase was homogeneous on ultracentrifugation and disc electrophoresis.

• Microbiology and Biotechnology Letters
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• 제31권2호
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• pp.151-156
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• 2003

A strain YB-10 was isolated from soil as a producer of the extracellular $\beta$-D-galactosidase, which catalyzes the hydrolysis of lactose. The strain YB-10 was identified as Streptomyces sp. on the basis of its cultural, morphological and physiological properties. After treating culture supernatant of the isolate with ammonium sulfate, the precipitated protein was used as a crude $\beta$-galactosidase for analyzing its reaction properties with para-nitrophenyl-$\beta$-D-galactosidase(pNP-$\beta$Gal) as a substrate. The $\beta$-galactosidase showed its maximal activity at pH 6.0 and 6$0^{\circ}C$. The enzyme was also active on lactose. The hydrolyzing activity of $\beta$-galactosldase for pNP-$\beta$Gal and lactose was decreased by galactose. Its hydrolyzing activity far lactose was also decreased by glucose, but the activity for pNP-$\beta$Gal was increased to 1.8-folds by glucose.

• Asian-Australasian Journal of Animal Sciences
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• 제17권12호
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• pp.1751-1757
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• 2004

Recombinant heterologous proteins can be produced as insoluble aggregates partially or perfectly inactive in Escherichia coli. One of the strateges to improve the solubility of recombinant proteins is fusion with a partner that is excellent in producing soluble fusion proteins. To improve the production of soluble $\beta$-galactosidase, the gene of Thermus thermophilus KNOUC112 $\beta$-galactosidase (KNOUC112 $\beta$-gal) was fused with thioredoxin gene, and optimization of its expression in E. coli TOP10 was performed. KNOUC112 $\beta$-gal in pET-5b was isolated out, fused with thioredoxin gene in pThioHis C, and transformed to E. coli TOP10. The $\beta$-galactosidase fused with thioredoxin was produced in E. coli TOP10 as dimer and trimer. The productivity of fusion $\beta$ -galactosidase expressed via pThioHis C at 37$^{\circ}C$ was about 5 times higher than that of unfused $\beta$-galactosidase expressed via pET-5b at 37$^{\circ}C$. Inclusion body of $\beta$-galactosidase was formed highly, regardless of the induction by IPTG when KNOUC112 $\beta$ -gal was expressed via pET-5b at 37$^{\circ}C$. Fusion $\beta$ -galactosidase expressed at 37$^{\circ}C$ via pThioHis C without the induction by IPTG was soluble, but the induction by IPTG promoted the formation of inclusion body. Lowering the incubation temperature for the expression of fusion gene under 25$^{\circ}C$ prevented the formation of inclusion body, optimally at 25$^{\circ}C$. 0.07 mM of IPTG was sufficient for the soluble expression of fusion gene at 25$^{\circ}C$. The soluble production of Thermus thermophilus KNOUC112 $\beta$-galactosidase could be increased about 10 times by fusion with thioredoxin, and optimization of incubation temperature and IPTG concentration for induction.

• Microbiology and Biotechnology Letters
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• 제15권2호
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• pp.84-88
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• 1987

Poly(ethylene glycol)-PPB two phase system was used tot the purification of $\beta$-galactosidase from Lactobacillus sporogenes. The smaller the molecular weight of concentration of PEG phase in-creased, proteins as well as $\beta$-galactosidase was partitioned into the top phase. All cell debris were confined to the potassium phosphate phase (bottom phase), approached to the binodial line. The purification ratio increased by changing the polymer-salt composition of the tie line towards higher salt concentrations. It was also possible to obtain higher purification of the enzyme after two-step extraction using PEG 1000 and PEG 300. The top phase contained 74% of the total $\beta$-galactosidase with a purification factor of 2.1.

• Korean Journal of Food Science and Technology
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• 제25권6호
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• pp.689-693
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• 1993

${\alpha}-galactosidase$ releases galactoside from raffinose and stachyose which are the major sugars in soybean, Although raffinose and stachyose were known as flatulence factors, these sugars were recently claimed as bifidus factors. In this experiment we studied the properties of ${\alpha}-galactosidase$ and its production from Bifidobacterium sp. Int-57. Int-57 produced higher level of ${\alpha}-galactosidase$ than other intestinal bacteria. The production of ${\alpha}-galactosidase$ was greater when grown on raffinose compared with other carbohydrates tested. Partially purified ${\alpha}-galactosidase$ was obtained after sonication of harvested cell pellet followed by DEAE-cellulose chromatography and Sepharose CL-6B gel filtration, and assayed using PNP-${\alpha}-galactosidase$ as a substrate. Optimum pH for activity was 7.0 and optimum temperature was $40^{\circ}C$. At 5 mM concentration of metal ions, $CoCl_{2}\;and\;CuCl_{2}$ and inhibited the enzyme activity by 33% and 21% respectively. The enzyme was shown to hydrolyse genuine substrates, i.e. raffinose and stachyose.

• Microbiology and Biotechnology Letters
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• 제17권6호
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• pp.587-592
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• 1989

A strain of alkalophilic Bacillus sp. YS-309 capable of producing large amount of $\beta$-galactosidase has been isolated from soil sample. Intracellular $\beta$-galactosidase was purified 6.9 folds by procedures including ammonium sulfate precipitation, DEAE-cellulose chromatography, gel-filtration, DEAE-Sephadex A-50 chromatography with over-all yield of 17.8%. The molecular weight of native enzyme was 205, 000 by HPLC, and SDS-polyacrylamide gel electrophoresis showed that the enzyme consisted of 4 identical subunits with a molecular weight of 56, 000.