• Journal of Life Science
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• v.27 no.8
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• pp.945-950
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• 2017

To some extent, the growth of solvent-tolerant Pseudomonas sp. BCNU 106 is limited by toxic solvents. Therefore, various strategies to overcome this limitation need to be investigated. One such strategy is to use exogenous trehalose. The highest intracellular trehalose content of 181.88 mM was measured at 12 hr. The extracellular trehalose content decreased rapidly within 12 to 16 hr in the presence of cyclohexane. Moreover, the number of Pseudomonas sp. BCNU 106 cells grown in Luria-Bertani (LB) broth supplemented with 0.1 M trehalose in the presence of 1%(v/v) cyclohexane, hexane, propylbenzene, and m-xylene increased 89.94-, 89.72-, 91.25-, and 118.9-fold, respectively, in comparison to the control level. High survival rates of 80% and 90% were observed in the presence of cyclohexane and hexane by the addition of 0.05 M trehalose for up to 4 hr, respectively. Exogenously-added trehalose was transported into the cells, and it conferred protection against cyclohexane, hexane, propylbenzene, and m-xylene. Adding exogenous trehalose to the growth medium improved the tolerance of Pseudomonas sp. BCNU 106; thus, it is a potential biocatalyst for biotransformation and biodegradation.

• Food Industry And Nutrition
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• v.2 no.1
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• pp.7-9
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• 1997

내열설 미생물, Thermus caldophilus CK24에 대한 탄수화물 생합성을 연구하는 과정에서 다양한 탄수화물 관련효소를 탐색하고 그레 대한 생화학적 및 분자생물학적 연구를 수행하고 있다. 일차로 내열성 미생물내 1) 당핵산염 합성효소와 당전이 효소, 2) 탄수화물 대사효소. 3)탄수화물 분해 및 전환효소의 존재를 HPLC/Bio-LC분석을 통하여 확인하고 이들에 대한 연구를 진행하고 있다. 본 연구발표에서는 포도당을 과당으로 전환하는 이성화효소(xylose isomerase), 그리고 맥아당을 트레할로스로 전환하는 트레할로스 합성효소(trehalose synthase)를 소개하고저 한다. 이성화효소는 이미 산업적 과당 생산에서 대규모적으로 사용되고 있는 식품산업효소이다. 본 연구에서는 Thermus caldophilus GK24, Thermus thermophilus HB8, Thermus flavus AT62 3종의 내열성 미생물에 대한 이성화효소 유전자를 클로닝 하고, 각 재조합하고 이성화효소를 대량생산하였다. 이 내열성 이성화효소는 최적 반응 온도가 8$0^{\circ}C$이고, 포도당을 과당으로 전환하는 수유른 55%이었다. 이러한 과당전환률은 이미 산업적으로 사용되고 있는 이성화효소의 과당전환률(43%)보다 훨씬 높은 것으로 과당 생산공정의 단순화의 생산성 향상에 결정적인 요인이라 할 수 있다. 한편 본 이성화효소의 산업적 특성을 증대하기 위하여 구조-기능관계 연구를 착수하였다. 우선 내열성 이산화 효소의 입체 구조를 결정하였고, 구조조정에 따른 기능적 특성을 조사하기 위하여 특정 위치의 선택적 변이 연구를 진행하고 있다. 끝으로 포도당 전이 효소를 추적하던 과정에서 맥아당을 트레할로스로 전환하는 새로운 효소를 Thermus caldo-philus GK24에서 발견하였다. 그 트레할로스 합성효소는 분자량이 약 110kDa이고 최적 반응온도가 75$^{\circ}C$이면, 조효소없이 맥아당을 트레할로스로 80%이상 전환해 주는 가역효소이었다. 본 연구에서는 효소반응의 조건과 특성을 조사하였고, 효소 아미노-밀단의 서열결정정보를 통하여 효소의 유전자를 클로닝 하고 그 유전자의 구조와 발현연구를 진행하고 있다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.3
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• pp.377-383
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• 2009

Texture and descriptive sensory characteristics of a Korean rice cake (Karedduk) added with mixture of trehalose and Sun-Tender were investigated after 2, 24, and 48 hrs of storage at $5^{\circ}C$. A central composite design was used for treatment arrangement. The trehalose were added in 0, 3, 6, 9 and 12% levels and Sun-Tender added in 0, 0.3, 0.6, 0.9, and 1.2% levels to dry rice flour. The mixture amounts of trehalose and Sun-Tender on texture and descriptive sensory characteristics of a Korean rice cake (Karedduk) were optimized using response surface methodology (RSM). The two independent variables selected for the RSM were amounts of trehalose ($X_1$) and amounts of Sun-Tender ($X_2$). The predicted value at stationary point or a minimum for texture hardness by RSM was found as 591.5440 after 24 hrs of storage at $5^{\circ}C$. Also the adhesiveness, hardness, cohesiveness and sweetness by sensory characteristics were significantly different as compared to the control. The results suggested that a Korean rice cake (Karedduk) added with mixture of trehalose and Sun-Tender can be made from the mixture amounts of trehalose 9.5826% and Sun-Tender 0.2216% in retarding retrogradation.

• Korean Journal of Food Science and Technology
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• v.50 no.3
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• pp.280-285
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• 2018

Lipid oxidation and antioxidant stabilities of nut-sesame yeotgangjeong (Korean traditional candy bar) with different binders were evaluated during storage in the dark. S1, S2, and S3 binders consisted of starch syrup, sugar, and water (58:34:7.6, w/w/w); starch syrup, jocheong, honey, trehalose, and water (43.5:11.6:2.9:34:7.6, w/w/w/w/w); and starch syrup, jocheong, honey, sugar, trehalose, and water (43.5:11.6:2.9:17:17:7.6, w/w/w/w/w/w); respectively. Lipid oxidation was determined by peroxide and p-anisidine values, and tocopherol, lignan, and polyphenol contents were determined spectrophotometrically. Peroxide values were significantly higher (p<0.05) in yeotgangjeong samples with S2 or S3 binder than in those with S1; however, the converse was true for tocopherol degradation. Lignan was the most stable antioxidant in yeotgangjeong. The results suggest that tocopherols have a priority over lignans to control the lipid oxidation of yeotgangjeong during storage; reduced lipid oxidative stability after substituting sugar with trehalose might be because it increases oxygen diffusivity and inhibits the antioxidant action of tocopherols on lipids.

• KSBB Journal
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• v.21 no.4
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• pp.298-301
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• 2006

A gene(GeneBank AF 135796) coding for a trehalose synthase from Thermus caldophilus GK24 was cloned into Escherichia coli K12 using five vector systems. The constitutive expression system(pHCETS) which shows the highest trehalose synthase activity from flask culture of recombinant E. coli was selected for the production of trehalose from maltose. For the shake flask culture, the final dry cell weight was 0.9 g/L and the trehalose synthase activity was 25 U/mL. Fed-batch culture of recombinant E. coli harboring plasmid pHCETS which uses the glycerolas a carbon source was performed in jar fermentor: the dry cell weight of 20 g/L and the trehalose synthase activity of 13.7 U/mL were attained in 48 h.

• Microbiology and Biotechnology Letters
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• v.36 no.3
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• pp.182-188
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• 2008

A hyperthermophilic bacteria (strain HJ6) was isolated from a hot springs located in the Arima-cho, Hyogo, Japan. The cells were long-rod type ($2-4{\mu}m$), about $0.4{\mu}m$ in diameter. The pH and temperature for optimal growth were 6.5 and $80^{\circ}C$, respectively. Phylogenetic analysis based on the 16S rDNA sequence and biochemical studies indicated that HJ6 belonged to the genus Thermus thermophilus (Tt). The gene encoding the Trehalose synthase (TS) was cloned and sequenced. The open reading frame (ORF) of the TtTS gene was composed of 2,898 nucleotides and encoded a protein (975 amino acids) with a predicted molecular weight of 110.56 kDa. The deduced amino acid sequence of TtTS showed 99% and 83% identities to the Thermus caldophilus TS and Meiothermus ruber TS, respectively. TtTS gene was expressed in Escherichia coli cells, and the recombinant protein was purified to homogeneity. The optimal temperature and pH for Trehalose synthase activity were found to be $80^{\circ}C$ and 7.5, respectively. The half-life of heat inactivation was about 40 min at $90^{\circ}C$. The maximum trehalose conversion rate of maltose into trehalose by the enzyme increased as the substrate concentration increased, and reached 55.7% at the maltose concentration of 500 mM, implying that the enzyme conversion was dependent of the substrate concentration.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.10
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• pp.1320-1325
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• 2007

Retarding retrogradation of a Korean rice cake (Karedduk) added with carbohydrate materials after $0{\sim}30hrs$ of storage at $5^{\circ}C$ were investigated by Avrami equation using textural characteristics. Carbohydrate materials such as powdered sugar, trehalose, fructooligosaccharide (95%), isomalto, healtholigo, and galactooligo-saccharide (50%) were added in 0, 1, 5 or 10% levels on dry rice flour. In the amylogram, the breakdown (P-H) and consistency (C-H) for Karedduk added with carbohydrate materials were lower than those of the control. Decrease in the Avrami exponent (n) and increase in the time constant (1/k) of Karedduuk added with carbohydrate materials during storage determined by Avrami equation were important comparison factors to the control in terms of retrogradation rate analysis. The Aurami exponent (n) for control, fructooligosaccharide (95%) 10% and healtholigo 1% addition were 2.415, 1.977 and 3.297, respectively. The time constant (1/k) for fructooligosaccharide (95%) 5% and healtholigo 1% addition were lower than thecontrol. Lastly, Karedduk added with carbohydrate materials, except for fructooligosaccharide (95%) 5% and healtholigo 1% addition, was effective in retarding retrogradation.

• Microbiology and Biotechnology Letters
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• v.44 no.3
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• pp.341-348
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• 2016

This study aimed to develop a microbial process for producing aminolevulinic acid (ALA) using crude glycerol. In the culture of ALA-producing cells (Escherichia coli/pH-hemA) in a medium containing crude glycerol, the cell density and production were 1.8-fold and 1.2-fold lower than those obtained from pure glycerol, respectively. However, the cell growth and production were improved by supplementing the medium with trehalose (30 or 100 g/l). Engineered cells (E. coli/pH-hemA/pS-otsBA) were constructed to express otsBA and their culture performance was compared with that of control cells (E. coli/pH-hemA/ pSTV28). The effects of isopropyl β-D-1-thiogalactopyranoside (IPTG) concentration and the time of induction were examined to improve the cell growth and ALA production in engineered cells cultured using crude glycerol. When 0.6 mM of IPTG was added at the beginning of the exponential growth phase, the ALA produced by cells was 2,121 mg/l, which was comparable to that from pure glycerol. The results demonstrate that otsBA expression endowed cells with the capacity to tolerate the toxicity of crude glycerol for direct use.

• Korean Journal of Food Science and Technology
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• v.53 no.6
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• pp.739-748
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• 2021

This study focuses on the use of rice in the production of gluten-free rice udon (GFU) through an optimized mixing ratio, using the Box-Behnken response surface methodology (RSM). Different additional levels of rice flour (A, 40-60 g), acetylated distarch adipate (B, 10-20 g), and trehalose (C, 0-3 g) were used as variables, while water absorption level, volume, cooking loss, solid yield, lightness, texture properties, proximate compositions of GFU and turbidity of cooking water were set as responses in the RSM design model. The optimum mixing ratio for the preparation of gluten-free rice udon was obtained for 60.00 g of rice flour, 18.81 g of acetylated distarch adipate without the addition of trehalose. The response values of the optimized samples were water absorption (60.94%), volume (34.94%), turbidity of the cooking water (0.37), cooking loss (4.77%), solid yield (1.55 g), lightness value (70.04), hardness (2.53 N), springiness (0.18), gumminess (10.45 N), chewiness (1.83 N), and cohesiveness (2.89). This study has shown that rice flour can replace wheat flour to manufacture udon at an optimized mixing ratio successfully derived by statistical estimation method.

• Journal of the Korean Chemical Society
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• v.48 no.2
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• pp.171-176
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• 2004

We investigated the activity and stability of alcohol oxidase from Hansenula sp. under the electric stimulation. The activity and stability of alcohol oxidase depended on electric output voltage, stimulation time, pulse duration and pulse interval. This inactivation of the enzyme under electric stimulation could be recovered by stabilizing additives such as sugars, polymers and hydrogels. The enzyme activity retained about 52% in 10% trehalose solution under electric stimulation with 40 V and 10 min. The stabilizing of enzymes against electric stimulation showed a great potential use of enzymes in biotechnology and medical engineering fields.