• Microbiology and Biotechnology Letters
• /
• v.29 no.3
• /
• pp.169-175
• /
• 2001

This study was conducted to investigate the effects of bifidobacteria on the growth and Caco-2 cell-adherence of Escherichia coli O157:H7 .Dur-ing momo-culture of E. coli O157:H7 and mixed culture with Bifidobacterium infantis K9, pH viable cell count, and ammonia concentration were measured Co-cultivation of E. coli O157:H7 with bifidobacteria. producing acidic metabolites rapidly decreased the viable cell count of E. coli O157:H7 In addition rapid decrease of ammo- nia concentration was observed during mixed culture after 8 hrs incubation compared to single culture of E. coli O157:H7 Therefore it is likely that bifidobacteria assimilate ammonia produced by E. coli O157:H7 P4 B, infantis K9 showed quite similar adherence on the Caco-2 cells in either case. On the other hand adherence of E. coli O157:H7 decreased from 2.6% to 1.86% when B infantis K9 was adhered to Caco-2 cell 2 hrs prior to the application of E. coli O157:H7 In conclusion in adherence of E coli O157:H7 to Caco -2 cell was inhibited by competition of its binding to the adherence site with bifidobacteria. In addition inhibitory effects of bifidobacteria on E coli O157:H7 appeared to be much higher with increae of the number of bifidobacteria and its ability of adherence to Caco-2 cells.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.33 no.3
• /
• pp.571-575
• /
• 2004

Escherichia coli O157:H7 cause hemorrhagic colitis and the extraintestinal complication of hemolytic-uremic syndrome, with their higher incidence occurring in children. Lipopolysaccharide (LPS) of E. coli O157:H7 is very important to make IgG anti-LPS with bactericidal activity. To identify the characteristic of E. coli OI57:H7, we isolated 60 MDa plasmid and amplified stx genes of shiga-like toxin (Stx) 1, 2 of E. coli O157:H7 by polymerase chain reaction (PCR) method. Using the simple purification method which contained phenol extract, ethanol precipitation and gel filtration steps, the LPS of E. coli O157:H7 was isolated and purified. Finally, we confirmed the purity of LPS through SDS-PAGE and silver nitrate staining.

• The Korean Journal of Food And Nutrition
• /
• v.14 no.3
• /
• pp.263-268
• /
• 2001

NaIO$_4$-산화 전분당을 Bacillus licheniformis의 $\alpha$-아밀라아제의 반응시켜서 시프염기 형성으로 당단백질로 변형시켜서 안정성을 확인하였다. 10$0^{\circ}C$에서의 열안정성은 10분 뒤에, pH 9.7에서 변형한 효소 비변형 효소의 순으로 높았다. 그러나 변형 및 안정성에 $\alpha$-cyclodextrin($\alpha$-CD)을 사용한 결과 큰 차이는 나지 않았다. pH 8.0에서 $\alpha$-CD 존재하에 변형한 효소는 pH 8~11dml 알칼리쪽에서 가장 높은 안정성을 나타냈으나, pH 5~7사이에는 다른 효소보다 낮았다. pH 9.7에서 변형하지 않은 효소는 pH 5부터 pH 13까지 서서히 증가하였고 pH 9.7에서 $\alpha$-CD존재 하의 효소는 pH 5부터 7까지 증가하다가 그 후 pH13까지 서서히 감소하였다. $\alpha$-CD존재하의 비변형 효소는 pH 7과 10에서 피크를나타낸 다음 pH12이후에는 급격히 낮아졌다. 변형한 효소는 HPLC 의 유출시간이 빨라wu서 변형하지 않은 효소보다 분자량이 큰 것으로 나타났다. 분자량 크기는 비변형 효소

• Journal of the Korea Organic Resources Recycling Association
• /
• v.19 no.3
• /
• pp.73-78
• /
• 2011

The pH is one of the most important factors affecting metabolism pathway and activity of hydrogen producing bacteria. The effect of operational pH on anaerobic hydrogen fermentation of food waste was evaluated at mesophilic condition. In this batch experiment, the initial pH was 8.0 and the operational pH was controlled at 4.7~7.0 by the addition of 5N KOH solutions. At the operational pH of 4.7, the lag phase and the maximum hydrogen production were 47.9h and 534.4 mL, respectively. The lag phase and the maximum hydrogen production were decreased as the operational pH increased. At the operational pH of 7.0, the lag phase and the maximum hydrogen production were 4.2 h and 213.8 mL, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.20 no.4
• /
• pp.178-184
• /
• 2010

The $12CaO{\cdot}7Al_2O_3$(C12A7) powders were successfully synthesized using combustion method with microwave-assistant and C12A7:H were fabricated by post-annealed process in Ar/H atmosphere. X-ray diffraction patterns and TGDSC were used for investigating to the precursors of crystalline and reaction depending on temperature. C12A7:H that was treated post-annealed process were investigated TG-MS and Hall-measurement for confirming H ions doping and checking electrical resistivity of C12A7:H. H ion substituted to $O^{2-}$ ions in the C12A7 cages were confirmed at $289.5^{\circ}C$ by TG-MS and C12A7:H calcined at $1000^{\circ}C$ in Ar/H=8:2 atmosphere for 8~10 h has low electrical resistivity about $10^2{\Omega}{\cdot}cm$ at room temperature.

• Journal of Food Hygiene and Safety
• /
• v.28 no.3
• /
• pp.272-278
• /
• 2013

To evaluate the effect of surface contaminated with Escherichia coli O157:H7 (E. coli O157:H7) on the microbiological safety of lettuce, this study was conducted to investigate the attachment, biofilm producing, survival, and cross-contamination of E. coli O157:H7 on stainless steel and polyvinyl chloride (PVC). The attachment rate of E. coli O157:H7 on PVC was 10 times higher than that on stainless steel after exposure 1 h in cell suspension. However, there was not a difference between two types of surface after exposure for 6 h and 24h. The biofilm producing of E. coli O157:H7 was TSB > 10% lettuce extracts > 1% lettuce extracts > phosphate buffer. When two kinds of materials were stored at various conditions ($20^{\circ}C$ and $30^{\circ}C$, relative humidity (RH) 43%, 69%, and 100%), the numbers of E. coli O157:H7 at $30^{\circ}C$, RH 43% or RH 69% were reduced by 5.0 log CFU/coupon within 12 h regardless of material type. Conversely, the survival of E. coli O157:H7 at RH 100% was lasted more than 5 days. In addition, the reduction rate of E. coli O157:H7 was decreased in the presence of organic matter. The transfer efficiency of E. coli O157:H7 from the contaminated surface to lettuce was dependent upon the water amount of the surface of lettuce. Especially, the transfer rate of E. coli O157:H7 was increased by 10 times in the presence of water on the lettuce surface. From this study, the retention of E. coli O157:H7 on produce contact surfaces increase the risk cross-contamination of this pathogen to produce. Thus, it is important that the surface in post harvest facility is properly washed and sanitized after working for prevention of cross-contamination from surface.

• Food Science of Animal Resources
• /
• v.36 no.2
• /
• pp.186-193
• /
• 2016

This study aimed to inhibit Escherichia coli (E. coli) O157:H7 artificially contaminated in fresh meat using bacteriophage. Among 14 bacteriophages, the highly lytic bacteriophage BPECO19 strain was selected to inhibit E. coli O157:H7 in artificially contaminated meat samples. Bacteriophage BPECO19 significantly reduced E. coli O157:H7 bacterial load in vitro in a multiplicity of infection (MOI)-dependent manner. E. coli O157:H7 was completely inhibited only in 10 min in vitro by the treatment of 10,000 MOI BPECO19. The treatment of BPECO19 at 100,000 MOI completely reduced 5 Log CFU/cm² E. coli O157:H7 bacterial load in beef and pork at 4 and 8h, respectively. In chicken meat, a 4.65 log reduction of E. coli O157:H7 was observed at 4 h by 100,000 MOI. The treatment of single bacteriophage BPECO19 was an effective method to control E. coli O157:H7 in meat samples.

• Journal of the Korean Chemical Society
• /
• v.34 no.6
• /
• pp.534-538
• /
• 1990

Chromium(Ⅵ) compound, [$C_9H_7$NH]$_2Cr_2O_7$ has been prepared by the reaction of isoquinoline with chromium trioxide under the presence of water. [$C_9H_7$NH]$_2Cr_2O_7$ is nonhydroscopic and dissolved in water very well. Structure of [$C_9H_7$NH]$_2Cr_2O_7$ is identified by FTIR spectra and elemental analysis data. The ability of [$C_9H_7$NH]$_2Cr_2O_7$ for the oxidation of alcohols were examined in methylene chloride. [$C_9H_7$NH]$_2Cr_2O_7$ was found as efficient oxidizing agent for the conversion of allyl, primary and secondary alcohols to the corresponding aldehydes or ketones.

• Archives of Pharmacal Research
• /
• v.12 no.1
• /
• pp.1-4
• /
• 1989

6-Arylamino-3,7-dihydro-3,7-dimethy-2-oxo-1H-purine and 2-arylimino-6-arylamino-3,7-dihydro-3,7-dimethyl-1H-purine were obtained in a one-pot reaction when 3,7-dihydro-3,7-dimethyl-1H-purine-3,6-dione, phosphorus pentaoxide, triethylamine hydrochloride and appropriate amine amino are heated at $170^{\circ}$. Some derivatives were tested for their antitumor activity.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.7 no.1
• /
• pp.1-7
• /
• 1987

A pot experiment conducted to investigate the root elongation and weight of grasses, i.e. Orchardgrass, tall fescue and perennial ryegrass under the conditions adjusted pH of half vertical part of pot soil to seven levels from 2 to 8. 1. Root growth was drastically decreased as soil pH was lowed. 2. Higer the soil pH, longer the root length. Increase of soil pH to 6 increased the root length of orchardgrass, perennial ryegrass and tall fescue. 3. Regardless of grass species, most of roots distributed to the soil which adjusted pH from 6 to 7. 4. Dry weight of root was increased to pH 7 of soil in orchardgrass and perennial ryegrass and was 55 to 78% of production of pH 6 compared with soil pH 7. In case of tall fescue, dry root weight in the soil pH 7 was 69.8% of root weight growed in soil pH 6.