Resistance of Bacillus cereus and Its Enterotoxin Genes in Ready-to-eat Foods to ${\gamma}$-Irradiation

Mtenga, Adelard B.,Kassim, Neema,Lee, Won-Gyeong,Shim, Won-Bo,Yoon, Yo-Han,Chung, Duck-Hwa 한국식품과학회 2012 Food Science and Biotechnology Vol.21 No.2

This study was investigated the resistance of Bacillus cereus ATCC 13752 and its enterotoxin coding genes in cereals, vegetables, and tryptic soy broth to ${\gamma}$-irradiation. Screening for enterotoxin coding genes, viability test, PCR analysis, measurement of DNA concentration, cellular constituents release, SEM, and antibiotic sensitivity tests were performed after irradiation at 0, 1.5, 3, 5, 7, 10, and 15 kGy. Thirty % of strains screened possessed all enterotoxins genes. At 10 kGy B. cereus viable cell count was reduced by 4 logCFU/mL. B. cereus in vegetables and broth demonstrated higher susceptibility than those in cereals. Enterotoxins coding genes could be identified in the ${\gamma}$-irradiated cells, antibiotic sensitivity profile was not affected. Concentration of DNA containing enterotoxin coding genes was reduced and release of cellular constituent was highest at 15 kGy. ${\gamma}$-Irradiation up to 10 kGy did not eliminate B. cereus neither affected their enterotoxins coding genes from ready-to-eat food.

Effect of Low Dose γ-Irradiation on the Fate and Cell Envelope of Bacillus cereus, Escherichia coli, and Salmonella Typhimurium

Mtenga, Adelard B.,Kassim, Neema,Lee, Won-Gyeong,Heo, Rok-Won,Shim, Won-Bo,Yoon, Yohan,Chung, Duck-Hwa Korean Society for Food Science of Animal Resource 2011 한국축산식품학회지 Vol.31 No.6

This study investigated the effect of low dose ${\gamma}$-irradiation on the damage of the cell envelopes and antibiotic sensitivity profiles of Bacillus cereus, Escherichia coli, and Salmonella Typhimurium. The bacteria suspension in tryptic soy broth was exposed to the ${\gamma}$-irradiation doses of 0, 1, 1.5, 3, and 5 kGy, and then stored at $0^{\circ}C$ for 24 h. A viability test, an antimicrobial sensitivity profile, and an electron microscopy were performed to observe the effects due to ${\gamma}$-irradiation treatment. B. cereus could survive the ${\gamma}$-irradiation up to 5 kGy while E. coli and S. Typhimurium were all deactivated at 1.5 kGy and 5 kGy, respectively. At 5 kGy, the cell count of B. cereus was significantly reduced, and the survived bacteria cells retained their important features. There were no significant changes observed in the antimicrobial sensitivity profile (p>0.05) for the recovered bacteria after irradiation treatment. Low dose ${\gamma}$-irradiation below 3 kGy was found to be insufficient to achieve decontamination of B. cereus and S. Typhimurium. Cell envelope damage and deactivation of different bacteria did not occur in the same manner; thus, deferent doses of ${\gamma}$-irradiation may be required for deactivation of different bacteria.

不均衡假說檢證 : 美國의 貸付市場을 中心으로

尹源培 숙명여자대학교 경제연구소 1984 論文集 Vol.13 No.-

Disequilibrium hypothesis is tested by estimating the structural equations for the U.S.A. loan market in the context of the newly developed disequilibrium econometric model. The hypothesis that the loan market is, on the average, in the disequilibrium state is accepted on a time series which includes commercial and industrial loans outsanding of U.S.A. An important finding is that the downward adjustment speed is faster than the upward adjustment speed. The implication may be that the economy, when faced with loan market disequilibrium, responds more rapidly to monetary contraction than to monetary expansion. In connection wtih credit rationing, if we consider the money market to be imperfectly competifive or oligopolistic, i.e., banks are price setters, then we can say that the banks adjust the interest rate upward more slowly than downward for two reasons: the possibility of increasing default of firms which can cause a loss to banks. and the high disequilibrium cost for banks in case of excess supply.

Lactobacillus helveticus CU 631을 이용한 Probiotic Cream Cheese 생산

송의한,원병렬,윤영호 한국동물자원과학회 2001 한국축산학회지 Vol.43 No.6

위장질환 원인균인 H. pylori를 강하게 억제하는 L. helveticus CU 631을 이용하여 새로운 형태의 probiotics cream cheese를 제조하고 이화학적 성분 및 미생물수의 변화와 단백질 분해 및 물성, 기호도 변화 성향을 분석하였다. Cream cheese의 화학성분 조성은 수분 54.9%±0.3, 지방 32.1%±0.1, 단백질 10.5%±0.07. 회분 1.0%±0.06을 나타내었으며, 선발된 L. helveticus CU 631의 probiotic 미생물 생균수는 7.1×10^6cfu/g과 3.3×10^7cfu/g 수준이었으며 4주간 숙성과정에서 1.7×10^7cfu/g에서 3.3×10^7cfu/g 수준으로 생균수의 증가를 나타내었다. starter로 이용된 Lactococcus spp. 생균수는 숙성기간중 5.6×10^8cfu/g에서 7.6×10^4cfu/g으로 감소하는 경향을 보였다. HLPC에 의한 수용성 peptide 측정결과 L.helveticus CU 631 첨가에 의하여 총 peak 수가 증가하며 생균수 10^6cfu/g인 C-2의 경우보다 10^7cfu/g 생균수인 C-3에서 peak 수가 현저하게 많은 것으로 나타나 단백질 분해 정도가 높았다. 숙성 진전에 따른 peptide 분해정도 차이를 총 peak 면적측정에 의하여 비교한 결과 cream cheese와 probiotic cream cheese의 모든 시료에서 4주 숙성이후 peak 면적이 현저하게 증가하여 단백질의 peptide로 분해가 진전된 결과를 나타내었다. 수용성질소 및 비단백태 질소 함유율은 유사한 수준으로 함유되었고 전기 영동 pattern은 cream cheese과 probiotic cream cheese band 간에는 뚜렷한 차이를 보이지 않았으나 숙성이후 1주와 4주 이후의 분해정도의 차이는 크게 나타나 단백질 분해활성의 차이를 나타내었다. Cream cheese의 경도, 탄력성, 결착성, 점착성 및 저작성은 probiotic cream cheese보다 낮은 성향을 나타내었으며 cream cheese의 경우 숙성기간 경과에 따라 증가성향을 보였다. C-2와 C-3 등 probiotic cream cheese가 높은 선호도를 나타낸 반면 cream cheese의 경우 맛과 풍미 면에서 통계적인 유의성이 없는 수준의 차이로 낮은 수치를 보였다. Lactobacillus helveticus CU 631, which has antagonistic effects against Helicobacter pyroli, was used to make cream cheese. The characteristics of the product and changes during the ripening period was studied. The moisture, fat, protein and ash content of probiotic cream cheese have been analyzed as 54.9%±0.3, 32.1%±0.1, 10.5%±0.07. and 1.0%±0.06. The viable cell counts of starter and probiotic organism of the final product was 7.6 ×10^4cfu/g in Lactococcus lactis and 3.3×10^7cfu/g in Lactobacillus helveticus. During the 4 weeks of ripening period, Lactococcus counts decreased by 4 log cycles from 1.6×10^8cfu/g to 7.7×10^4cfu/g, and Lactobacillus counts increased by two fold. Water soluble peptides were determined by HPLC, the more numerable peaks of peptides of probiotic cream cheese appeared than those of cream cheese on HPLC chromatogram, and revealed a larger total peak area of 4-week ripened product than 1-week ripened cheese. a statistically significant difference in peak number and peak area in chromatogram occured, hence an extensive proteolysis has been occured during the ripening by the probiotic organisms. Changes in water soluble and non protein nitrogen content was determined and changes in protein during ripening period analyzed by SDS polyacrylamide electrophoresis. The rheological properties of the probiotic cheese were determined, values in hardness, springiness, cohesiveness, gumminess and chewiness tended to increase ripening proceeds. The probiotic cream cheese(C-2, C-3) got a better preference results than cream cheese(c-1) with no statistical significance.

Lactobacillus helveticus CU 631 에 의한 Helicobacter pylon 의 Urease 및 공포 생성 독소 억제활성

송의한,원병렬,윤영호,강경희,장명웅 한국동물자원과학회 2001 한국축산학회지 Vol.43 No.6

표준균주 혹은 유제품으로부터 분리된 Lactobacillus spp.와 Bifidobacterium spp. 32균주를 사용하여 H. pylori 생장을 현저하게 억제하는 L. helveticus CU631을 선발하고, urease와 공포생성 독소의 활성을 억제하는 효과를 측정하여 다음의 결과를 얻었다. L. helveticus CU631의 억제대의 직경이 10.0±1.5㎜ 나타내어 가장 강력한 생장 억제 능력을 보였으며 L. plantarum과 L. fermentum은 직경 4.0㎜ 내외의 억제대를 나타내어 비교적 약한 억제 활성을 보였으며 Bifidobacterium spp.에서 억제 활성을 보이지 않았다. L. helveticus CU631의 배양액과 배양 상층액 모두, H. pylori NCTC11637의 urese 억제 활성을 나타내었다. L. helveticus CU631를 H. pylori G88016를 같이 배양했을시 공포생성 독소의 역가가 50%로 감소하였으며 L. helvesticus CU631의 배양 상층액과 H. pylori G88016의 배양 상층액을 5:5와 6:4 비율로 혼합하였을 때 억제 활성이 나타났다. The inhibitory effects of 32 strains of lactobacilli against Helicobacter. pylori were determined and Lactobacillus. helveticus CU631 has been selected as the strain which possessed the strongest inhibitory effect against H. pylori NCTC11637 in inhibition zone test showing inhibition zone with the average diameter of 10±1.5㎜, whereas Lactobacillus. plantarum and L. fermentum made inhibition zone with the average diameter of 4.0㎜, H. pylori G88016 revealed the highest vacuolating toxin activity among the 8 strains of H. pylori, which showed positive reaction of vacuolating toxin gene in PCR amplification test. Both L. helveticus CU631 and cell free culture supernatant had a strong inhibitory activity on the urease activity of H. pylori NCTC11637. The inhibitory activity of L. helveticus CU631 on the vacuolating toxin activity of H. pylori manifested in the co-culture of two strains and in the 5:5 mixture of supernatant of the two strains.

DNA Probe를 利用한 Yersinia enterocolitica의 早期診斷法 開發에 관한 硏究(Ⅰ)

閔洪基,金昌珉,吳好貞,韓惠勝,丁大映,崔圭實,尹性植,崔徹淳,李欽淑,元奉必 국립보건연구원 1992 국립보건원보 Vol.29 No.2

Yersinia enterocolitica의 조기진단법 개발에 관한 연구

민홍기,성원근,홍성화,김창민,이춘근,오호정,최규실,안현신,김성자,윤성식,원봉필 국립보건연구원 1994 국립보건원보 Vol.31 No.2

Effect of irradiation on kinetic behavior of <i>Salmonella</i> Typhimurium and <i>Staphylococcus aureus</i> in lettuce and damage of bacterial cell envelope

Shim, Won-Bo,Je, Gil-Soo,Kim, Kyeongyeol,Mtenga, Adelard B.,Lee, Won-Gyeong,Song, Jeong-Un,Chung, Duck-Hwa,Yoon, Yohan Elsevier 2012 Radiation physics and chemistry Vol.81 No.5

<P><B>Abstract</B></P><P>This study evaluated effect of gamma irradiation on survival of <I>Salmonella Typhimurium</I> and <I>Staphylococcus aureus</I> on lettuce and damage of cell envelope. <I>S.</I> Typhimurium and <I>S. aureus</I> were inoculated on red leaf lettuce, and they were irradiated at 0, 0.5, 1, 1.5, 2, 2.5, and 3kGy, and the samples were then stored at 7 and 25°C for 7 days. Survival of <I>S.</I> Typhimurium and <I>S. aureus</I> were enumerated on xylose lysine deoxycholate agar and Baird–Parker agar, respectively. <I>D</I><SUB>10</SUB> value (dose required to reduce 1log CFU/leaf) was calculated, and kinetic parameters (maximum specific growth rate; <I>μ</I><SUB>max</SUB> and lag phase duration; LPD) were calculated by the modified Gompertz model. In addition, cell envelope damage of the pathogens was observed by scanning electron microscope (SEM) and transmission electron microscope (TEM). <I>D</I><SUB>10</SUB> values were 0.35 and 0.33kGy for <I>S.</I> Typhimurium and <I>S. aureus</I>, respectively. During storage at 7°C, <I>S.</I> Typhimurium and <I>S. aureus</I> had significant (<I>P</I><0.05) growth only on non-irradiated samples up to about 2.5 and 4log CFU/leaf at 0.42 and 1.28log CFU/leaf/day of <I>μ</I><SUB>max</SUB>, respectively. At 25°C, cell counts of <I>S.</I> Typhimurium and <I>S. aureus</I> on the samples irradiated at 0 and 0.5kGy increased (<I>P</I><0.05) up to 3–6log CFU/leaf. The <I>μ</I><SUB>max</SUB> of both pathogens were higher in 0kGy <I>(</I>1.08–2.27log CFU/leaf/day) and 0.5kGy (0.58–0.92log CFU/leaf/day), and LPDs ranged from 1.53 to 3.14 day. SEM and TEM observations showed that cells irradiated at 1.5 and 3kGy showed disrupted cell membrane. These results indicate that gamma irradiation could be a useful decontamination technology to improve food safety of lettuce by destroying cells of <I>S.</I> Typhimurium and <I>S. aureus</I>.</P> <P><B>Highlights</B></P><P>► Low dose of gamma irradiation destroyed cell envelope of the pathogens. ► Gamma irradiation decreased cell counts of the pathogens on lettuce. ► Gamma irradiation could be useful in improving food safety of lettuce.</P>

DNA damage induced apoptosis suppressor (DDIAS) is upregulated via ERK5/MEF2B signaling and promotes β-catenin-mediated invasion

Im, J.Y.,Yoon, S.H.,Kim, B.K.,Ban, H.S.,Won, K.J.,Chung, K.S.,Jung, K.E.,Won, M. Elsevier Science 2016 Biochimica et biophysica acta. Gene regulatory mec Vol.1859 No.11

DNA damage induced apoptosis suppressor (DDIAS) is an anti-apoptotic protein that promotes cancer cell survival. We previously reported that DDIAS is transcriptionally activated by nuclear factor of activated T cells 2 (NFATc1). However, the upstream regulation of DDIAS expression by growth factors has not been studied. Here, we demonstrate that DDIAS expression is induced by extracellular signal-regulated kinase 5 (ERK5) and myocyte enhancer factor 2B (MEF2B) in response to epidermal growth factor (EGF) and that it positively regulates β-catenin signaling in HeLa cells. The genetic or pharmacological inhibition of ERK5 suppressed DDIAS induction following EGF exposure and the overexpression of constitutively active MEK5 (CA-MEK5) enhanced DDIAS expression. In chromatin immunoprecipitation assays, MEF2B, a downstream target of ERK5, exhibited sequence-specific binding to a MEF2 binding site in the DDIAS promoter following treatment with EGF. The overexpression of MEF2B increased the EGF-mediated induction of DDIAS expression, whereas the knockdown of MEF2B impaired this effect. Furthermore, DDIAS promoted invasion by increasing β-catenin expression at the post-translational level in response to EGF, suggesting that DDIAS plays a crucial role in the metastasis of cancer cells by regulating β-catenin expression. It is unlikely that MEF2B and NFATc1 cooperatively regulate DDIAS transcription in response to EGF. Collectively, EGF activates the ERK5/MEF2 pathway, which in turn induces DDIAS expression to promote cancer cell invasion by activating β-catenin target genes.

Effect of Temperature and Concentration on Rheological Behavior of Xanthan-Carob Mixed Gels

Yoon, Won-B.,Gunasekaran, Sundaram Korean Society for Biotechnology and Bioengineerin 2007 Biotechnology and Bioprocess Engineering Vol.12 No.3

The gelation and melting behavior of 1:1, 1:3 xanthan-carob mixed gels were evaluated at isothermal and non-isothermal states, as a function of total polymer concentrations of 0.1, 0.5, and 1%. A thermal hysteresis was observed between gelation and melting. The higher the polymer concentration, the higher the melting temperature. The gelation points were determined by three criteria. Depending on the criterion used the gelation temperature was different (52 to $70^[\circ}C$). Pseudo-equilibrium modulus and elastic active network chain (EANC) concentration were calculated from the plateau modulus in the frequency spectrum. Temperature dependence of the monomeric friction coefficient was estimated from the relaxation time and EANC. Time-temperature superposition theory was not applicable due to dramatic phase transitions occurring during the gelation of X/C mixture.