• Microbiology and Biotechnology Letters
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• v.44 no.4
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• pp.504-511
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• 2016

Lactulose, a synthetic disaccharide, has received increasing interest because of its role as a prebiotic that can increase the proliferation of Bifidobacterium and Lactobacillus spp. and enhance the absorption of calcium and magnesium. While the industrial production of lactulose is still mainly achieved by the chemical isomerization of lactose in alkaline media, this process has drawbacks including the need to remove catalysts and by-products, as well as high energy requirements. Recently, the use of cellobiose 2-epimerase (CE) has been considered an interesting alternative for industrial lactulose production. In this study, to develop a process for enzymatic lactulose production using CE, we screened improved mutant enzymes ($CS-H^RC^E$) from a library generated by an error-prone PCR technique. The thermostability of one mutant was enhanced, conferring stability up to $75^{\circ}C$, and its lactulose conversion yield was increased by 1.3-fold compared with that of wild-type CE. Using a recombinant Escherichia coli strain harboring a CS35 $H^RC^E$-expressing plasmid, we prepared cell beads immobilized on a Ca-alginate substrate and optimized their reaction conditions. In a batch reaction with 200 g/l lactose solution and the immobilized cell beads, lactose was converted into lactulose with a conversion yield of 43% in 2 h. In a repeated 38-plex batch reaction, the immobilized cell beads were relatively stable, and 80% of the original enzyme activity was retained after 4 cycles. In conclusion, we developed a reasonable method for lactulose production by immobilizing cells expressing thermostable CE. Further development is required to apply this approach at an industrial scale.

• Journal of Microbiology and Biotechnology
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• v.18 no.8
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• pp.1386-1392
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• 2008

A gene (sll0158) putatively encoding a glycogen branching enzyme (GBE, E.C. 2.4.1.18) was cloned from Synechocystis sp. PCC6803, and the recombinant protein expressed and characterized. The PCR-amplified putative GBE gene was ligated into a pET-21a plasmid vector harboring a T7 promoter, and the recombinant DNA transformed into a host cell, E. coli BL21(DE3). The IPTG-induced enzymes were then extracted and purified using Ni-NTA affinity chromatography. The putative GBE gene was found to be composed of 2,310 nucleotides and encoded 770 amino acids, corresponding to approx. 90.7 kDa, as confirmed by SDS-PAGE and MALDI-TOF-MS analyses. The optimal conditions for GBE activity were investigated by measuring the absorbance change in iodine affinity, and shown to be pH 8.0 and $30^{\circ}C$ in a 50 mM glycine-NaOH buffer. The action pattern of the GBE on amylose, an $\alpha$-(1,4)-linked linear glucan, was analyzed using high-performance anion-exchange chromatography (HPAEC) after isoamylolysis. As a result, the GBE displayed $\alpha$-glucosyl transferring activity by cleaving the $\alpha$-(1,4)-linkages and transferring the cleaved maltoglycosyl moiety to form new $\alpha$-(1,6)-branch linkages. A time-course study of the GBE reaction was carried out with biosynthetic amylose (BSAM; $M_p{\cong}$8,000), and the changes in the branch-chain length distribution were evaluated. When increasing the reaction time up to 48 h, the weight- and number-average DP ($DP_w$ and $DP_n$) decreased from 19.6 to 8.7 and from 17.6 to 7.8, respectively. The molecular size ($M_p$, peak $M_w{\cong}2.45-2.75{\times}10^5$) of the GBE-reacted product from BSAM reached the size of amylose (AM) in botanical starch, yet the product was highly soluble and stable in water, unlike AM molecules. Thus, GBE-generated products can provide new food and non-food applications, owing to their unique physical properties.

• IMMUNE NETWORK
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• v.3 no.2
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• pp.126-135
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• 2003

Background: One of the important factors in the prognosis of chronic hepatitis B patient is the degree of replication of hepatitis B virus (HBV). It has been known that HBV DNA polymerase plays the essential role in the replication of HBV. HBV DNA polymerase is composed of four domains, TP (Terminal protein), spacer, RT (Reverse transcriptase) and RNaseH. Among these domains, tyrosine, the $65^{th}$ residue of TP is an important residue in protein-priming reaction that initiates reverse transcription. If monoclonal antibody that recognizes around tyrosine residue were selected, it could be applied to further study of HBV replication. Methods: To produce TP-specific scFv (single-chain Fv) by phage display, mice were immunized using synthetic TP-peptide contains $57{\sim}80^{th}$ amino acid residues of TP domain. After isolation of mRNA of heavy-variable region ($V_H$) and light-chain variable region ($V_L$) from the spleen of the immunized mouse, DNA of $V_H$ and $V_L$ were obtained by RT-PCR and joined by a DNA linker encoding peptide (Gly4Ser)3 as a scFv DNA fragments. ScFv DNA fragments were cloned into a phagemid vector. scFv was expressed in E.coli TG1 as a fusion protein with E tag and phage gIII. To select the scFv that has specific affinity to TP-peptide from the phage-antibody library, we used two cycles of panning and colony lift assay. Results: The TP-peptide-specific scFv was isolated by selection process using TP-peptide as an antigen. Selected scFv had 30 kDa of protein size and its nucleotide sequences were analyzed. Indirect- and competitive-ELISA revealed that the selected scFv specifically recognized both TP-peptide and the HBV DNA polymerase. Conclusion: The scFv that recognizes the TP domain of the HBV DNA polymerase was isolated by phage display.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.42-50
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• 2006

역들의 공간적 분포가 불균질하고 역의 크기가 큰 역암의 경우 암석 전체를 대표하는 물성치($E_m,\;c,\;\Phi$ 등) 구하기 위해서는 매우 큰 시험기기가 필요하다. 따라서 커다란 역을 포함하는 역암의 경우 직접 암석실내시험을 통한 물성치 산정은 현실적으로 거의 불가능하다. 이러한 문제를 극복하기 위하여 이 연구에서는 개별요소법을 이용하여 역암의 물성치를 산출하는 방법을 제안한다. 그 방법은다음과 같다. (1) 역암내의 역의 물성과 기질부의 물성을 각각 실내실험을 통하여 파악한 후 이들 (2) 두 물질의 거동양상을 구현할 수 있는 개별요소집합체의 개별요소간의 물성을 결정한다. (3) 역의 함량, 크기 모양 공간적 분포양상등의 역암 조직과 유사한 개별요소 수치해석시료를 만든 후, (4) 이를 수치 해석실험 (이축압축실험)에 사용한다. 이러한 수치해석실험을 통해 현재까지 만들어진 결과는 다음과 같다. 첫째, 역의 강도가 기질의 강도보다 높은 역암의 경우, 역의 양이 증가할수록 일축압축강도, 내부 마찰각, 점착력이 증가하지만 증가 양상은 선형이 아니다. 탄성계수의 경우 역의 양과 상관 없이 변화하지 않는다. 둘째, 역과 기질 사이 표면의 점착력이 약할 경우 이러한 표면에서 최초 미세 균열이 형성되기 시작하므로 이 점착력은 물성치를 산출하는 중요한 인자이다. 따라서, 향후 이에 대한 자세한 연구가 필요하다고 판단된다. 결론적으로,설계 또는 시공시 직접시험에 의한 물성치의 파악이 어려운 역암 또는 직접시험을 위해 대량의 시료를 필요로 하는 함력 미고결지층, 핵석층, 풍화암과 같은 시료의 물성치는 별도로 측정된 물성들 (예, 역과 기질)을 이용한 개별요소법을 통해 구할 수 있다.로 나타났다.TEX>, DIN/DIP비 표층수 $23.91\pm3.42$, 저층수 $23.43\pm3.38$이었으며, 전반적으로 해역별 수질기준 I등급 내지는 II등급을 유지하고 있었고, 공간적으로는 외해측으로 갈수록 외해수와 혼합 확산되어 양호한 수질을 나타내었다. 장기적인 변동특성은 세그룹으로 구분되어진다.기 실험결과 용출용매로 증류수와 해수를 이용했을 때, 제강 슬래그에서 용출되는 납, 구리, 카드뮴, 수은의 용출 경향의 차이를 확인할 수 있었고 이에 따라서, 납, 구리, 카드뮴의 용출 유해성은 낮기 때문에 해양구조물로의 제강슬래그 유효이용은 적합할 것으로 판단되었다.im80%$로 계산되었다. 열형광선량계로 측정된 방사선량은 각각 1.8, 1.2, 0.8, 1.2, 0.8 (70 cm 거리) cGy로 측정되었으며, 환자의 복부 표면에서의 서베이메터를 이용한 측정량은 10.9 mR/h였다. 차폐구조물의 사용 시 전체 치료 동안에 태아선량은 약 1 cGy 정도로 평가되었다. 결론 : AAPM Report No.50의 자료에 따르면, 임산부의 방사선 치료 시 태아의 방사선 피폭선량은 5 cGy 이하일 경우에 방사선 피폭에 따른 태아의 위험이 거의 없는 것으로 제시되고 있다. 본원에서 차폐 구조물을 설치하였을 경우에 측정된 태아선량은 약 1 cGy로 측정되었고, 고안된 차폐구조물은 태아에 도달하는 방사선량을 감소시키기에 적합한 설계임이 입증되었다. 아니라 일반종합병원에서도 CTX-M형 ESBL 생성 E. coli와 K. pneumoniae가 존재하며 확산 중임을 시사한다. 앞으로 CTX-M형 ESBL의 만연과 변종 CTX-M형 ESBL의 출연을 감시하기 위한

• Journal of agricultural medicine and community health
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• v.10 no.1
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• pp.36-41
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• 1985

To evaluate the parasitic infection rates among inhabitants in urban area of Seoul, Korea, a total of 5,275 stool and anal swab specimens was obtained from 2,527 male and Z,748 female living in 24 Dongs of 17 Kus. Cases were sampled randomely to represent 1,000 inhabitants refereed to the census in 1980. The methods employed were formalin ether technique to detect helminth ova and protozoan cysts and scotch tape anal swab technique to detect eggs of Enterobius vermicularis. The results obtained are as follows ; 1) Total positive rate of helminthes was 23.5% among 5,275 (male 22.5% and female 24.5%) specimens. Nine kinds of the helminthes were detected and infection rates of each helminth were; Ascaris lumbricoides 4.1%, Hookworm 0.1%, Trichuris trichiura 11.1%, Trichostrongylus orientalis 0.1%. Clonorchis sinensis 1.2%, Metagonimus yokogawai 0.1%, Taenia spp. 0.2%, Hymenolepis nana 0.3 and Enterobius vermicularis 9.6%. 2) Total positive rate of intestinal protozoa was 1.4%. Four kinds of the protozoan cysts were detected and the infection rates of each protozoa were; Entamoeba histolytica 0.15%, E. coli 0.4%, Endolimax nana 0.04% and Giardia lamblia 0.89%. 3) No significant differences in the parasitic infection rate by sex was noticed although male group showed lower infection rate than female group. However the incidence of C. sinensis, M. yokogawai and Taenia spp. was twice as much in female group as in male group. 4) No difference in the infection rate by age was found although E. vermicularis positive rate was highest in "0~9 years group" by 2.1% and C. sinensis infection rate was higher in over "30~39 years group". The parasitic infection rate of the present study was significantly lower than those of previous reports in Seoul area and other provinces.

• Food Science of Animal Resources
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• v.21 no.2
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• pp.149-155
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• 2001

The aims of this study were to examine contamination sources and provide the basic data in establishment of sanitary standard for raw pork meat. From \"Random sampling(I)\", initial total plate counts of post-slaughter samples for the group A, B and C were 1.5${\times}10^4$cfu/$textrm{cm}^2$, 5.5${\times}10^5$cfu/$textrm{cm}^2$ and 1.8${\times}10^4$cfu/$textrm{cm}^2$, respectively, and of post-prechilling samples for the group A, B and C were 1.0${\times}10^4$cfu/$textrm{cm}^2$, 4.6${\times}10^5$cfu/$textrm{cm}^2$ and 2.5${\times}10^4$cfu/$textrm{cm}^2$, respectively. Initial total plate counts of post-transportation samples for the group D, E and F did not increased, as did the group A, B and C. From \"Normal sampling(II)\", initial total plate counts of post-slaughter, post-prechilling, post-transportation and post-2 days preservation samples were 7.3${\times}10^4$cfu/$textrm{cm}^2$, 9.6${\times}10^4$cfu/$textrm{cm}^2$, 2.0${\times}10^5$cfu/$textrm{cm}^2$ and 2.5${\times}10^5$cfu/$textrm{cm}^2$, respectively. From \"Clean sampling(III)\", initial total plate counts of post-slaughter, post-prechilling, post-transportation and post-2 days preservation samples were decreased to 7.0${\times}10^2$cfu/$textrm{cm}^2$, 7.5${\times}10^2$cfu/$textrm{cm}^2$, 8.5${\times}10^2$cfu/$textrm{cm}^2$ and 5.5${\times}10^3$cfu/$textrm{cm}^2$, respectively, compared with "Normal sampling(II)". No E. coli O157:H7, Staphylococcus aureus and Salmonella were detected at each sampling step. Consequently, a slaughter method like "Clean sampling(III)" showed a better sanitary effect to low total plate counts of 10$^2$∼10$^3$times, compared with "Normal sampling(II)". The one of contamination sources for raw pork meat was at a slaughtering step, and "Clean sampling" method may be considered as the one of sanitary standards.

• KSBB Journal
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• v.17 no.2
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• pp.153-157
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• 2002

A fusion protein, consisting of a human epidermal growth factor as the recognition domain and human angiogenin as the toxin domain, can be used as a targeted therapeutic against breast cancer cells among others. The fusion protein was expressed as an inclusion body in recombinant E. coli, yet when the conventional solution-phase refolding process was used the refolding yield was very low due to severe aggregation, probably because of the opposite surface charge resulting from the vastly different pl values of each domain. Accordingly the solid-phase refolding process, which exploits the ionic interactions between a solid matrix and the protein, was tried, however the ionic binding yield was also very low regardless of the resins and pH conditions used. Therefore, to provide a higher affinity toward the solid matrix, six Iysine residues were tagged to the N-terminus of the hEGF domain. When cation exchange resins, such as heparin- or CM-Sepharose, were used as the matrix, the adsorption capacity increased 2.5~3-fold and the subsequent refolding yield increased nearly 15-fold compared to the conventional process. A similat result was also obtained when an Ni-NTA metal affinity resin was used.

• Journal of Animal Science and Technology
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• v.44 no.6
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• pp.711-718
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• 2002

In order to investigate the effect of feeding browses on the incidence of abortion in pregnant Korean native female goats, 20 pregnant does(3${\sim}$4 month) were used as experimental animal and they grouped 4 treatments with 5 heads according to experimental diets. Each group was fed pine browse, pine browse silage, fermented pine browse, or oak browse silage. Browses intake a day was 0.36kg for oak browse silage, 0.28kg for pine browse, 0.24kg for pine browse silage, and 0.14kg for fermented pine browse. Salmonella and Fungi were not found in pine browses but they were found in oak browse silage in the amount of 7.93${\times}$$10^3$ and 11.1${\times}$$10^1$ cfu/g, respectively. E. Coliwas found 11.67${\times}$$10^1$cfu/g in oak browse silage. The incidence of abortion was 60% for fermented pine browse, 40% for pine browse silage, and 20% for pine browse feeding. Abortion did not occur by feeding oak browse silage. Progesterone concentration was similar each other regardless of normal delivery or abortion at delivery day but the concentration of estradiol was higher for normal delivery, concentration of cortisol was decreased until the delivery day in normal but increased in abortion does. The results were suggested.

• The Korean Journal of Food And Nutrition
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• v.27 no.3
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• pp.348-357
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• 2014

This study was carried out to evaluate the yield of extract, antioxidant compounds (total phenolic and total flavonoid), antioxidant (DPPH assay, ABTS assay and reducing power), and antimicrobial activities of bracken (Pteridium aquilinum Kuhn), according to cooking methods (non-blanched, blanched and seasoned). The yield of seasoned bracken extracts showed a high value of (4.59%) followed by non-blanched bracken and blanched bracken with 2.69% and 0.30%, respectively. In the total polyphenol and flavonoid contents, seasoned bracken extracts showed higher antioxidant compounds ($96.11{\pm}0.34mg\;GAE$/100 g RW, $20.90{\pm}0.mg\;CE$/100 g RW) than non-blanched and blanched. The total antioxidant activities (DPPH assay, ABTS assay and reducing power) were shown to be in the order of seasoned bracken > non-blanched bracken > blanched bracken. In the antimicrobial activities, non-blanched bracken extracts showed antimicrobial activity against B. cereus, B. subtilis, E. cloacae, E. coli, S. enterica, and P. aeruginosa except for S. aureus. The non-blanched bracken extracts (5 and 10 mg/disc) especially showed strong antimicrobial activity against P. aeruginosa ($10.00{\pm}0.71$ and $10.25{\pm}0.35mm$). The inhibition zone diameter from the extracts of blanched bracken and seasoned bracken was not detected. Many seasonings added in the process of cooking can increase the antioxidant capacities. The overall results of this study demonstrate that the cooked bracken with seasoning would be the most efficient way of ingesting antioxidant compounds.

• KSBB Journal
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• v.24 no.3
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• pp.273-278
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• 2009

The purpose of this work was to investigate the antibacterial activity of Lactobacillus plantarum YK-9 isolated from fermented Kimchi. Morphological and biochemical characteristics of L. plantarum YK-9 were examined. Phylogenetic analysis using 16S rRNA sequencing was performed to identify the strain, and the strain could be assigned to Lactobacillus plantarum, designated as L. plantarum YK-9. The strain was registered in GenBank as [FJ669130]. During the incubation period of L. plantarum YK-9, the changes of bacterial growth and residual organic acids were monitored. HPLC was used to confirm the organic acids produced in the cultures as metabolites. L. plantarum YK-9 produced both lactic acid and acetic acid, which were responsible for the pH decrease during growth. Initial pH 7.0 of the cultures decreased to 3.6 at the incubation after 72 hours, and concentrations of lactic acid and acetic acid increased to approximately 588.7 mM and 255.5 mM, respectively. The antibacterial activities against food-poisoning causing bacteria were examined with 20-fold concentrated culture supernatants from L. plantarum YK-9, and the antibacterial effects were clearly observed against all the bacteria tested in this work.