• Korean Journal of Food Science and Technology
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• v.22 no.2
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• pp.129-133
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• 1990

The strain of Nuruk yeat No. 15 (NY-15) which ferments lactose in milk was Isolated from Nuruk and identified as Saccharomyces marxianus according to the API 20C profile index. The lactose hydrolysing ability of NY-15 was similar to that Saccharomyces fragilis ATCC 8583 which has ${\beta}-galactosidase$ activity. Its optimum growth temperature, pH and time for the production of maximum enzyme activity showed $28^{\circ}C$, 4.5 and 28hr, respectively. Galactose as well as sucrose as carbon sources, and urea as nitrogen source Increased the production of enzyme. In order to test the production of alcohol, NY-15 was inoculated in whey medium and whey medium added with sugar. In the former, NY-15 produced 2% alcohol and in the latter, it showed 12% alcohol production. The optimal medium pH for lactose hydrolysis of NY-15 is 4.5, whereas that of Saccharomyces fragilis ATCC 8583 is 3.5

• Microbiology and Biotechnology Letters
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• v.11 no.1
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• pp.15-21
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• 1983

This experiment was carried out to optimize the condition for the enzyme production by selected strain in the basal medium, to purify the enzyme and to characterize the purified enzyme. The results obtained were as follows. 1. The optimal conditions for the $\beta$-galactosidase production were initial pH 7.0 and temperature $65^{\circ}C$. 2. Enzyme was induced by the addition of lactose and galactose, and it was intracellular enzyme. 3. The purified enzyme was obtained with the increased level of activity approximately 28.5 folds as compared with crude enzyme and the yield of 15.2% by means of DEAE-Cellulose column chromatography, Sephadex G-150 gel filtration 4. $\beta$-galactosidase from final step of purification showed a sing1e protein band on polyacrylamide gel disc electrophoresis. 5. The optimal temperature and pH of the purified enzyme were $65^{\circ}C$, pH 6.5 for the hydrolysis of lactose.

• Food Science and Biotechnology
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• v.16 no.1
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• pp.127-132
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• 2007

[ ${\alpha},\;{\alpha}$ ]-Trehalose was efficiently modified by a transgalactosylation reaction of Escherichia coli ${\beta}-galactosidase$ using lactose as a donor to yield two galactosyl trehalose trisaccharides. The reaction products of trehalose by the enzyme were observed by thin layer chromatography (TLC) and high performance anion exchange chromatography (HPAEC) and were purified by BioGel P2 gel permeation chromatography and recycling preparative HPLC. Liquid chromatography-mass spectrometry (LC-MS) and ^{13}C$ nuclear magnetic resonance (NMR) analyses revealed that the structures of the main products were $6^2-{\beta}-D-galactosyl$ trehalose (1) and $4^2-{\beta}-D-galactosyl$ trehalose (2). A reaction of 30%(w/v) trehalose and 15%(w/v) lactose at pH 7.5 and $45^{\circ}C$ resulted in a total yield of approximately 27-30% based on the amount of trehalose used. The galactosyl trehalose products were not hydrolyzed by trehalose. In addition the mixture of transfer products (9:1 ratio of 1 to 2) showed higher thermal stability than glucose, lactose, and maltose, but less than trehalose, against heat treatment over $100^{\circ}C$ at pH 4 and 7. It also exhibited better thermal stability than sucrose at pH 4 alone.

• Archives of Pharmacal Research
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• v.24 no.5
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• pp.416-417
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• 2001

A new triterpene lactose named patrinolide A (7) has been isolated from the roots of Patrinia scabiosaefolia (Valerianaceae). Its structure was determined to be 11$\beta$,21$\beta$-dihydroxy-3-oxooleanan-28,13$\beta$-olide on the basis of spectral analysis, including 2D-NMR techniques.

• Microbiology and Biotechnology Letters
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• v.42 no.4
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• pp.339-346
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• 2014

A bacterial strain was isolated from homemade doenjang (Korean fermented soybean paste) as a producer of the extracellular ${\beta}$-galactosidase, capable of hydrolyzing lactose to liberate galactose and glucose residues. The isolate YB-1414 has been identified as Bacillus licheniformis on the basis of its 16S rDNA sequence, morphology and biochemical properties. The production of ${\beta}$-galactosidase by B. licheniformis YB-1414 reached maximum levels of 6.2 U/ml in culture medium containing wheat bran (1%) and yeast extract (2.5%) as carbon and nitrogen sources, respectively. Particularly, the insoluble fraction was more effective for ${\beta}$-galactosidase production than the soluble extract of wheat bran. The enzyme exhibited maximum activity for hydrolysis of para-nitrophenyl-${\beta}$-D-galactopyranoside (pNP-${\beta}Gal$) under reaction conditions of pH 6.0 and $55-60^{\circ}C$. Its hydrolyzing activity for pNP-${\beta}Gal$ was drastically decreased by the addition of low concentrations of galactose, but only slightly decreased by glucose, with 85% of maximal activity in the presence of 400 mM glucose.

• Journal of Food Hygiene and Safety
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• v.2 no.2
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• pp.67-73
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• 1987

Kluyveromyces fragilis로부터 $\beta$-galactosidase의 생성조건과 조효소액의 성질 그리고 당 전이 반응에 의한 oligosaccharide 생성을 조사한 결과 다음과 같은 결과를 얻었다. \circled1 Peptone-Yeast extract 배지에 6% lactose를 첨가하였을 때 최대 효소생산을 보였다. \circled2 0.05 M potassium phosphate buffer (pH 7.0)에서 3% toluene를 첨가하여 37$^{\circ}C$ 5시간 배양하였을 때 K. fragilis로부터 효소가 최대로 추출되었다. \circled3 효소의 최적온도는 4$0^{\circ}C$이고 4$0^{\circ}C$ 이상의 열처리에서는 효소가 파괴되었으며, pH6-7에서는 상당히 안정하였다. \circled4 ONPG 기질로 사용하였을 때 Km 값은 2.5mM이었다. \circled5 당 전이 반응의 결과, 7개의 oligosaccharide가 생성되었다. 이상의 실험결과로 볼 때, 본 실험에 사용한 K. fragilis SKD 7001은 Beta-galactosidase의 생산을 위해서 이용 가치가 인정되었으며, 특히, 이 효소의 활성이 중성 pH에서 강하고 안정한 상태를 보이는 것은 시유나 원료우유의 lactose를 중성에서 해야 한다는 점을 고려할 때, 실용적 가치가 있다고 본다. 또, 이 효소의 작용과정에서 생성되는 oligosacchride는 장내 bifidus균의 생육을 촉진시키는 효과가 인정되고 있기 때문에 이용가치를 더욱 높여주는 것으로 생각된다.

• KSBB Journal
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• v.9 no.4
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• pp.400-405
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• 1994

The conditions for ${\beta}$-galactosidase production from alkalophilic, thermophilic Bacillus sp. TA-11 were investigated. The maximal enzyme production was obtained when the strain was cultured at $50^{\circ}C$ for 5 days with fed-batch culture in the optimal medium containing 1.5% lactose, 0.6% yeast extract 0.15% $K_2HP0_4$and initial pH 9.5, and then final enzyme activity under the above conditions was 5200 unit/ml of cell free extract.

• KSBB Journal
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• v.11 no.3
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• pp.317-322
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• 1996

Galactooligosaccharlde (GOS) is a kind of functional oligosaccharides that can be used as a food ingredient and a cosmetic additive. In this paper, characteristics of GOS synthesis by cellulase, using lactose as a substrate, were investigated. Penicillium funiculosum cellulose was found to be the most efficient for GOS production among six cellulose tested. The optimum pH and temperature for GOS production were 5.0 and $50^{\circ}C$, respectively. There was an optimum ratio of lactose concentration to enzyme loading; the value was 10 (w/w). The reaction pattern of P. funiculosum cellulase is consistent with that of microbial ${\beta}$-galactosidase which shows transgalactosylation activity. Amounts of GOS produced from 20% (w/v) lactose after 6 h incubation at $50^{\circ}C$, were 23% (w/w) based on total saccharide in the reaction medium. The GOS % increased with initial lactose concentration in the range of 5 to 20%. The products mainly consisted of a trisaccharide and tetrasaccharide from HPLC and TLC analysis. Among enzymes involved in transgalactosylation reaction, high molecular weight fractions over 50,000 Da, presumably ${\beta}$-glucosldase, were considered to be responsible for GOS production. Using this cellulose, a direct synthesis of galactosyl g1ucoside including GOS could be readily achieved with lactose as a galactosyl donor.

• Microbiology and Biotechnology Letters
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• v.40 no.1
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• pp.17-22
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• 2012

A bacterial strain was isolated from homemade Cheongkookjang as a producer of the ${\beta}$-galactosidase, capable of hydrolyzing lactose to liberate galactose and glucose residues. The isolate YB-1105 has been identified as Bacillus licheniformis on the basis of its 16S rDNA sequence, morphology and biochemical properties. ${\beta}$-Galactosidase activity was detected in both the culture supernatant and the cell extract of B. licheniformis YB-1105. The enzymes of both fractions demonstrated maximum activity for hydrolysis of para-nitrophenyl-${\beta}$-D-galactopyranoside (pNP-${\beta}Gal$) under identical reaction conditions of pH 6.5 and $50^{\circ}C$. However, ${\beta}$-galactosidase activity from the culture filtrate was affected more than that from the cell free extract at acidic pHs and high temperatures. The hydrolyzing activity of both ${\beta}$-galactosidases for pNP-${\beta}Gal$ was dramatically decreased by the addition of low concentrations of galactose, but was only marginally decreased by high concentrations of glucose or mannose.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.225-230
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• 2004

A plasminogen kringle domain 1 to 3, rKl-3, was expressed in Escherichia coli under the control of T7 promoter. For the cost-effective production of rKl-3, the induction process was analyzed and optimized. Induction characteristics with lactose were analyzed in terms of induction time and inducer concentration in various culture conditions including batch and high-cell-density fed-batch cultures. In the fed-batch culture, the induction around 6 h after initiation of the DO-stat fed-batch culture resulted in the highest expression level of rKI-3 among the induction points examined. The highest demand of oxygen at this point was crucial for the maximum expression level of rKI-3. As the lactose concentration increased, the expression level also increased, though the expression level showed a plateau above a concentration of 14 mM of lactose. Lactose acted less specifically than IPTG since most of it was hydrolyzed to glucose and galactose. However, using lactose, the cell growth and the maximum expression level of rKl-3 increased by 20% and 24%, respectively, compared with those using IPTG in the fed-batch culture. The lactose seemed to be hydrolyzed by intracellular and extracellular $\beta$-galactosidase liberated by cell lysis at the same time. Residual concentration of glucose was maintained to a a limit of detection by high performance liquid chromatography, and galactose was not consumed by the host strain Escherichia coli BL2l(DE3).