• Title, Summary, Keyword: Inactivation

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Effects of Pressure Assisted Mild Thermal Treatment on Inactivation of Escherichia coli ATCC 10536 in Milk Suspension

  • Park, S.H.;Hong, G.P.;Min, S.G.;Choi, M.J.
    • Food Science of Animal Resources
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    • v.29 no.3
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    • pp.310-316
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    • 2009
  • In this study, the influence of pressure assisted mild thermal inactivation (PAMTI) on E. coli ATCC 10536 was examined at 200 MPa and temperature range of $20-50^{\circ}C$. Inactivation rate significantly increased (p<0.05) as temperature and time increased at 200 MPa. The maximum inactivation (7.91 log reduction) was obtained at $50^{\circ}C$ for 30 min under 200 MPa, which meant the complete inactivation of E. coli ATCC 10536. Inactivation kinetics were evaluated with the first order inactivation rate (k), activation energy ($E_a$), thermal death time (TDT), and z value. Kinetic parameters were significantly (p<0.05) influenced by variation temperature of PAMTI. In this study, the synergistic effect of pressure and temperature were found in the inactivation of E. coli ATCC 10536 through PAMTI.

Effect of Salt Concentration and Turbidity on the Inactivation of Artemia sp. in Electrolysis UV, Electrolysis+UV Processes (해수의 염 농도와 탁도가 전기, UV 및 전기+UV 공정의 Artemia sp. 불활성화에 미치는 영향)

  • Kim, Dong-Seng;Park, Young-Seek
    • Journal of Environmental Science International
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    • v.28 no.3
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    • pp.291-301
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    • 2019
  • This study was conducted to investigate the effect of salt concentration and turbidity on the inactivation of Artemia sp. by electrolysis, UV photolysis, electrolysis+UV process to treat ballast water in the presence of brackish water or muddy water caused by rainfall. The inactivation at different salt concentrations (30 g/L and 3 g/L) and turbidity levels (0, 156, 779 NTU) was compared. A decrease in salt concentration reduced RNO (OH radical generation index) degradation and TRO (Total Residual Oxidant) production, indicating that a longer electrolysis time is required to achieve a 100% inactivation rate in electrolysis process. In the UV process, the higher turbidity results in lower UV transmittance and lower inactivation efficiency of Artemia sp. Higher the turbidity resulted in lower ultraviolet transmittance in the UV process and lower inactivation efficiency of Artemia sp. A UV exposure time of over 30 seconds was required for 100% inactivation. Factors affecting inactivation efficiency of Artemia sp. in low salt concentration are in the order: electrolysis+UV > electrolysis > UV process. In the case of electrolysis+UV process, TRO is lower than the electrolysis process, but RNO is more decomposed, indicating that the OH radical has a greater effect on the inactivation effect. In low salt concentrations and high turbidity conditions, factors affecting Artemia sp. inactivation were in the order electrolysis > electrolysis+UV > UV process. When the salt concentration is low and the turbidity is high, the electrolysis process is affected by the salt concentration and the UV process is affected by turbidity. Therefore, the synergy due to the combination of the electrolysis process and the UV process was small, and the inactivation was lower than that of the single electrolysis process only affected by the salt concentration.

Voltage-Dependent Inactivation of Calcium Currents in the Mouse Eggs

  • Park, Young-Geun;Yang, Young-Seon;Yum, Myung-Kul;Hong, Seong-Geun
    • The Korean journal of physiology & pharmacology
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    • v.25 no.2
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    • pp.125-131
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    • 1991
  • Inactivation properties of Ca current in the unfertilized eggs of mouse were studied by using the whole cell voltage clamp technique and single microelectrode voltage clamp technique. Membrane potential was held at -80 mV and step depolarization was applied from -50 mV to 50 mV for $200{\sim}500\;ms$. Peak of inward Ca currents was $-2{\sim}-4\;nA$ at a membrane Potentials from -20 mV to 0 mV and outward currents were not observed within the membrane voltage range studied $(-50{\sim}50\;mV)$. Inward currents were fully inactivated within 200 ms after the onset of step depolarization. As the membrane became depolarized, time constant of inactivation (${\tau}$) was decreased but remained around $20{\sim}30\;ms$ beyond 10 mV. When $Ca^{2+}$ was used as a charge earlier, inactivation of inward $Ca^{2+}$ current also occured and time course of inactivation was similar to that of $Ca^{2+}$ currents as charge carrier. In the bathing solution containing high potassium $(131\;mM\;K^+)$, process of inactivation was not changed except a parallel decrease of value for the entire range of membrane potential. Steady-state inactivation of the $current(h_{\infty})$ obtained from the double pulse experiment showed the voltage-dependent change. These results suggested that inactivation of Ca currents in the unfertilized eggs of mouse was voltage-dependent.

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X-Chromosome Inactivation: A Complex Circuits regulated by Non-coding RNAs and Pluripotent Factors

  • Hwang, Jae Yeon;Lee, Chang-Kyu
    • Reproductive and Developmental Biology
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    • v.41 no.2
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    • pp.33-40
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    • 2017
  • X-chromosome inactivation is one of the most complex events observed in early embryo developments. The epigenetic changes occurred in female X-chromosome is essential to compensate dosages of X-linked genes between males and females. Because of the relevance of the epigenetic process to the normal embryo developments and stem cell studies, X-chromosome inactivation has been focused intensively for last 10 years. Initiation and regulation of the process is managed by diverse factors. Especially, proteins and non-coding RNAs encoded in X-chromosome inactivation center, and a couple of transcription factors have been reported to regulate the event. In this review, we introduce the reported factors, and how they regulate epigenetic inactivation of X-chromosomes.

Divalent Cation-dependent Inactivation of N-type Calcium Channel in Rat Sympathetic Neurons (쥐 교감신경 뉴론 N형 칼슘통로의 2가 양이온의존성 비활성화)

  • Goo Yong-Sook
    • Progress in Medical Physics
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    • v.17 no.2
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    • pp.96-104
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    • 2006
  • Experiments from several groups Including ours have demonstrated that $Ca^{2+}$ can enhance the inactivation of N-type calcium channels. However, it is not clear if this effect can be ascribed to a 'classic' $Ca^{2+}$-dependent inactivation (CDI) mechanism. One method that has been used to demonstrate CDI of L-type calcium channels is to alter the intracellular and extracellular concentration of $Ca^{2+}$. In this paper we replaced the external divalent cation to monovalent ion ($MA^+$) to test CDI. In the previous paper, we could separate fast (${\tau}{\sim}150ms$) and slow (${\tau}{\sim}2,500ms$) components of inactivation in both $Ba^{2+}$ and $Ca^{2+}$ using 5-sec voltage step. Lowering the external divalent cation concentration to zero abolished fast inactivation with relatively little effect on slow inactivation. Slow inactivation ${\tau}$ correspond very well with provided the $MA^+$ data is shifted 10 mV hyperpolarized and slow inactivation ${\tau}$ decreases with depolarization voltage in both $MA^+\;and\;Ba^{2+}$, which consistent with a classical voltage dependent inactivation (VDI) mechanism. These results combined with those of our previous paper lead us to hypothesize that external divalent cations are required to produce fast N-channel inactivation and this divalent cation-dependent inactivation is a different mechanism from classic CDI or VDI.

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Inactivation of Bacteriophage f2 with Chlorine (염소에 의한 bacteriophage f2의 살균작용)

  • Chi Kyung KIM;Kyung Hee MIN
    • Korean Journal of Microbiology
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    • v.16 no.2
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    • pp.62-70
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    • 1978
  • Chlorine was used for inactivation of bacteriophage f2 at pH 5.5, 7.5, and 10.0 at $10^{\circ}C$. The inactivation rate phage with chlorine varied depending on the pH value and reaction time. Hypochlorous acid appeared to be the major species of free chlorine for the inactivation. Suevival of the phage treated with chlorine and infectivity of the RNA extracted from the chlorinated phage were examined. The RNA extracted from untreatd phage was chlorinated and its infectivity was assayed. All three samples showed similar rates of inactivation at pH 5.5 and 7.5, but the naked RNA was more susceptible to chlorine at pH 10.0. The rate of inactivation was compared naked RNA was more susceptible to chlorine at pH 10.0. The rate of inactivation was compared with specific and non-specific attachment of the phasge f2. The specific attachment of the phage increased after the phage had been inactivated by extended chlorination. Chlorine may penetrate to the becteriophage f2 by altering the structural integrity of the protein coat, but the main target of free chlorine for inactivation of the phage appeared to be the phage RNA.

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Disinfection Models to Predict Inactivation of Artemia sp. via Physicochemical Treatment Processes (물리·화학적 처리공정을 이용한 Artemia sp. 불활성화 예측을 위한 소독 모델)

  • Zheng, Chang;Kim, Dong-Seog;Park, Young-Seek
    • Journal of Environmental Science International
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    • v.26 no.4
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    • pp.421-432
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    • 2017
  • In this study, we examined the suitability of ten disinfection models for predicting the inactivation of Artemia sp. via single or combined physical and chemical treatments. The effect of Hydraulic Retention Time (HRT) on the inactivation of Artemia sp. was examined experimentally. Disinfection models were fitted to the experimental data by using the GInaFiT plug-in for Microsoft Excel. The inactivation model were evaluated on the basis of RMSE (Root Mean Square Error), SSE (mean Sum Square Error) and $r^2$. An inactivation model with the lowest RMSE, SSE and $r^2$ close to 1 was considered the best. The Weibull+Tail model was found to be the most appropriate for predicting the inactivation of Artemia sp. via electrolytic treatment and electrolytic-ultrasonic combined treatment. The Log-linear+Tail model was the most appropriate for modeling inactivation via homogenization and combined electrolytic-homogenization treatment. The double Weibull disinfection model was the most suitable for the predicting inactivation via ultrasonic treatment.

A Study on the Inactivation of Phytophthora Blight Pathogen (Phytophthora capsici) using Plasma Process (플라즈마 공정을 이용한 고추역병균(Phytophthora capsici) 불활성화에 관한 연구)

  • Kim, Dong-Seog;Park, Young-Seek
    • Journal of Environmental Science International
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    • v.23 no.9
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    • pp.1601-1608
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    • 2014
  • Plasma reactor was used for the inactivation of Phytophthora capsici which is phytophthora blight pathogen in aquiculture. Effects of first voltage, second voltage, air flow rate, pH, incubation water concentration were examined. At the low $1^{st}$ voltage, under 80 V, the lag phase was noticed within 30 sec, however, it was not shown over 100 V. The variation of optimum operation condition was not shown by the variation of microorganisms. However, the inactivation rate was different by the variation of species of microorganisms. The inactivation rate and efficiency were increased by the increase of $2^{nd}$ voltage. The highest initial inactivation rate was shown at pH 3 and the rate was decreased by the increase of pH. The inactivation rate increased by the increase of air flow rate, however, it was shown as similar at the rate of 4 L/min and 5 L/min. The inactivation rate was distinctly decreased at the three times concentration of incubation solution comparing at the distilled water and basic incubation solution.

Inactivation of Escherichia coli and MS2 coliphage by Cu(II)-activated peroxomonosulfate in natural water

  • Kim, Hyung-Eun;Lee, Hye-Jin;Kim, Min Sik;Choi, Joon-Young;Lee, Changha
    • Membrane Water Treatment
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    • v.10 no.3
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    • pp.231-237
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    • 2019
  • Peroxymonosulfate (PMS) in combination with Cu(II) was examined to inactivate E. coli and MS2 coliphage in natural water. The combined system (i.e., the Cu(II)/PMS system) caused a synergistic inactivation of E. coli and MS2, in contrast with either Cu(II) or PMS alone. Increasing the concentration of PMS enhanced the inactivation of E. coli and MS2, but after a certain point, it decreased the efficacy of the microbial inactivation. In the Cu(II)/PMS system, adding reactive oxidant scavengers marginally affected the E. coli inactivation, but the inhibitory effects of copper-chelating agents were significant. Fluorescent assays indicated that the Cu(II)/PMS system greatly increased the level of reactive oxidants inside the E. coli cells. The sequential addition of Cu(II) and PMS inactivated more E. coli than did adding the two simultaneously; in particular, the inactivation efficacy was much higher when Cu(II) was added first. The observations from the study collectively showed that the microbial inactivation by the Cu(II)/PMS system could be attributed to the toxicity of Cu(I) as well as the intracellular oxidative stress induced by Cu(III) or radical species.

Evaluation of Disinfection Characteristics of Ozone, UV Processes for Bacillus Subtilis Spores Inactivation (Bacillus Subtilis Spores 불활성화 실험을 통한 오존, UV 공정의 소독 특성 평가)

  • Jung, Yeon Jung;Oh, Byung Soo;Kang, Joon-Wun
    • Journal of Korean Society on Water Environment
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    • v.22 no.4
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    • pp.672-677
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    • 2006
  • Ozone/UV combined process is an effective technique to enhance generation of OH radical which is non-selective and powerful oxidant. The objective of this study is to evaluate the inactivation rates of B. subtilis spores by three candidate processes (ozone alone, UV alone, ozone/UV combined processes) at 4 and $20^{\circ}$ and to investigate the effects of OH radical on inactivation of B. subtilis spores. On the UV alone process, required UV dosages for lag phase and 3-log inactivation of B. subtilis spores were determined as $8.9mJ/cm^2$ and $47mJ/cm^2$. However, the inactivation of B. subtilis spores didn't occured beyond 4.5-log inactivation despite increasing UV dose. The inactivation of B. subtilis spores by ozone alone and ozone/UV combined process was investigated with ozone CT (Concentration of disinfectant ${\times}$ Contact time) concept. As a result, inactivation of B. subtilis spores by ozone/UV combined process was faster than by ozone alone, and especially $CT_{lag}$ value B. subtilis spores in the presence and absence of t-BuOH, OH radical scavenger, was investigated to evaluate effects of OH radical formed during ozone/UV combined process. We found that OH radical plays important roles on inactivation of B. subtilis spores.