TY  - JOUR
AU  - Šmigić, Nada
AU  - Rajković, Andreja
AU  - Arneborg, Nils
AU  - Siegumfeldt, Henrik
AU  - Devlieghere, Frank
AU  - Nielsen, Dennis Sandris
PY  - 2012
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/3024
AB  - The aim of this study was to investigate the response of Escherichia coli O157:H7 when exposed to different concentrations of sanitation agent chlorine dioxide (ClO2) by determining intracellular pH (pH(i)). For this purpose, fluorescence ratio imaging microscopy was used together with pH-sensitive, ratiometric green fluorescent protein that was introduced in E. coli O157:H7 cells. Along with pH(i), colony counts were determined during the treatment with ClO2. Results revealed several post-treatment subpopulations with different physiological states, as judged by their pH(i). The fraction of cells with no pH gradient increased, and the colony count decreased as the concentration of ClO2 increased.
PB  - Springer, New York
T2  - Food Analytical Methods
T1  - Analysis of Intracellular pH in Escherichia coli O157:H7 to Determine the Effect of Chlorine Dioxide Decontamination
EP  - 331
IS  - 3
SP  - 327
VL  - 5
DO  - 10.1007/s12161-011-9295-0
ER  - 

@article{
author = "Šmigić, Nada and Rajković, Andreja and Arneborg, Nils and Siegumfeldt, Henrik and Devlieghere, Frank and Nielsen, Dennis Sandris",
year = "2012",
abstract = "The aim of this study was to investigate the response of Escherichia coli O157:H7 when exposed to different concentrations of sanitation agent chlorine dioxide (ClO2) by determining intracellular pH (pH(i)). For this purpose, fluorescence ratio imaging microscopy was used together with pH-sensitive, ratiometric green fluorescent protein that was introduced in E. coli O157:H7 cells. Along with pH(i), colony counts were determined during the treatment with ClO2. Results revealed several post-treatment subpopulations with different physiological states, as judged by their pH(i). The fraction of cells with no pH gradient increased, and the colony count decreased as the concentration of ClO2 increased.",
publisher = "Springer, New York",
journal = "Food Analytical Methods",
title = "Analysis of Intracellular pH in Escherichia coli O157:H7 to Determine the Effect of Chlorine Dioxide Decontamination",
pages = "331-327",
number = "3",
volume = "5",
doi = "10.1007/s12161-011-9295-0"
}

Šmigić, N., Rajković, A., Arneborg, N., Siegumfeldt, H., Devlieghere, F.,& Nielsen, D. S.. (2012). Analysis of Intracellular pH in Escherichia coli O157:H7 to Determine the Effect of Chlorine Dioxide Decontamination. in Food Analytical Methods
Springer, New York., 5(3), 327-331.
https://doi.org/10.1007/s12161-011-9295-0

Šmigić N, Rajković A, Arneborg N, Siegumfeldt H, Devlieghere F, Nielsen DS. Analysis of Intracellular pH in Escherichia coli O157:H7 to Determine the Effect of Chlorine Dioxide Decontamination. in Food Analytical Methods. 2012;5(3):327-331.
doi:10.1007/s12161-011-9295-0 .

Šmigić, Nada, Rajković, Andreja, Arneborg, Nils, Siegumfeldt, Henrik, Devlieghere, Frank, Nielsen, Dennis Sandris, "Analysis of Intracellular pH in Escherichia coli O157:H7 to Determine the Effect of Chlorine Dioxide Decontamination" in Food Analytical Methods, 5, no. 3 (2012):327-331,
https://doi.org/10.1007/s12161-011-9295-0 . .

TY  - JOUR
AU  - Šmigić, Nada
AU  - Rajković, Andreja
AU  - Arneborg, Nils
AU  - Siegumfeldt, Henrik
AU  - Devlieghere, Frank
AU  - Nielsen, Dennis Sandris
PY  - 2011
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/2683
AB  - The aim of this study was to investigate the response of Campylobacter jejuni at single-cell level when exposed to different concentrations of chlorine dioxide (ClO2). The parameter of choice, intracellular pH (pH(i)), was determined by using fluorescence ratio imaging microscopy with a pH-sensitive, ratiometric 5(6)-carboxyfluorescein diacetate succinimidyl ester probe. In addition, the culturability expressed in colony counts was determined. Our results revealed that several subpopulations with different physiological states, as judged by their pHi, were created by ClO2 treatment. The greater the concentration of ClO2, the smaller the subpopulation of healthy cells with pH(i)>6.8 and the smaller the colony count as determined on nonselective agar plates. ClO2 at concentrations (60 ppm) induced injuries that resulted in complete loss of culturability and adversely affected the ability to resuscitate under subsequent more favorable conditions. The presence of injured cells in food could present a risk for public health. Additional hurdles have to be included in food preservation to suppress the survival and recovery of injured cells.
PB  - Mary Ann Liebert, Inc, New Rochelle
T2  - Foodborne Pathogens and Disease
T1  - Intracellular pH in Campylobacter jejuni When Treated with Aqueous Chlorine Dioxide
EP  - 328
IS  - 2
SP  - 325
VL  - 8
DO  - 10.1089/fpd.2010.0604
ER  - 

@article{
author = "Šmigić, Nada and Rajković, Andreja and Arneborg, Nils and Siegumfeldt, Henrik and Devlieghere, Frank and Nielsen, Dennis Sandris",
year = "2011",
abstract = "The aim of this study was to investigate the response of Campylobacter jejuni at single-cell level when exposed to different concentrations of chlorine dioxide (ClO2). The parameter of choice, intracellular pH (pH(i)), was determined by using fluorescence ratio imaging microscopy with a pH-sensitive, ratiometric 5(6)-carboxyfluorescein diacetate succinimidyl ester probe. In addition, the culturability expressed in colony counts was determined. Our results revealed that several subpopulations with different physiological states, as judged by their pHi, were created by ClO2 treatment. The greater the concentration of ClO2, the smaller the subpopulation of healthy cells with pH(i)>6.8 and the smaller the colony count as determined on nonselective agar plates. ClO2 at concentrations (60 ppm) induced injuries that resulted in complete loss of culturability and adversely affected the ability to resuscitate under subsequent more favorable conditions. The presence of injured cells in food could present a risk for public health. Additional hurdles have to be included in food preservation to suppress the survival and recovery of injured cells.",
publisher = "Mary Ann Liebert, Inc, New Rochelle",
journal = "Foodborne Pathogens and Disease",
title = "Intracellular pH in Campylobacter jejuni When Treated with Aqueous Chlorine Dioxide",
pages = "328-325",
number = "2",
volume = "8",
doi = "10.1089/fpd.2010.0604"
}

Šmigić, N., Rajković, A., Arneborg, N., Siegumfeldt, H., Devlieghere, F.,& Nielsen, D. S.. (2011). Intracellular pH in Campylobacter jejuni When Treated with Aqueous Chlorine Dioxide. in Foodborne Pathogens and Disease
Mary Ann Liebert, Inc, New Rochelle., 8(2), 325-328.
https://doi.org/10.1089/fpd.2010.0604

Šmigić N, Rajković A, Arneborg N, Siegumfeldt H, Devlieghere F, Nielsen DS. Intracellular pH in Campylobacter jejuni When Treated with Aqueous Chlorine Dioxide. in Foodborne Pathogens and Disease. 2011;8(2):325-328.
doi:10.1089/fpd.2010.0604 .

Šmigić, Nada, Rajković, Andreja, Arneborg, Nils, Siegumfeldt, Henrik, Devlieghere, Frank, Nielsen, Dennis Sandris, "Intracellular pH in Campylobacter jejuni When Treated with Aqueous Chlorine Dioxide" in Foodborne Pathogens and Disease, 8, no. 2 (2011):325-328,
https://doi.org/10.1089/fpd.2010.0604 . .

TY  - JOUR
AU  - Šmigić, Nada
AU  - Rajković, Andreja
AU  - Nielsen, Dennis Sandris
AU  - Arneborg, Nils
AU  - Siegumfeldt, Henrik
AU  - Devlieghere, Frank
PY  - 2010
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/2302
AB  - As mild decontamination treatments are gaining more and more interest due to increased consumer demands for fresh foods, it is of great importance to establish the influence of decontamination treatments on the subsequent bacterial behaviour under suboptimal storage conditions. For this purpose Campylobacter jejuni cells treated with lactic acid (LA, 3% lactic acid, pH 4.0, 2 min) or chlorine dioxide (ClO2, 20 ppm, 2 min) were inoculated in Bolton broth (pH 6.0) and incubated under 80% O-2/20% N-2, 80% CO2/20% N-2, air or micro-aerophilic (10% CO2/85% N-2/5% O-2) atmosphere, at 4 degrees C during 7 days. Treatment with water served as a control. The most suppressive atmosphere for the survival of C jejuni was O-2-rich atmosphere, followed by air, micro-aerophilic and CO2-rich atmosphere. The survival of C. jejuni was dependent on the type of initial decontamination treatment, with water treated cells showing the greatest survival followed by LA and ClO2 treated cells. Intracellular pH (pH(i)) of individual C. jejuni cells was determined using Fluorescence Ratio Imaging Microscopy (FRIM). At all tested conditions, different subpopulation of the cells could be distinguished based on their pH(i) values. The pH(i) response was independent on the surrounding atmosphere since similar distribution of the subpopulations was observed for all tested atmospheres. However, the pH(i) response was dependent on the initial decontamination treatment. The investigation of intracellular parameters gave an insight into pathogen behaviour under stressful conditions at intracellular level. The results obtained in this study highlighted the importance of combining decontamination technologies with subsequent preservation techniques to the control survival and growth of foodborne pathogens.
PB  - Elsevier, Amsterdam
T2  - International Journal of Food Microbiology
T1  - Survival of lactic acid and chlorine dioxide treated Campylobacter jejuni under suboptimal conditions of pH, temperature and modified atmosphere
EP  - S146
SP  - S140
VL  - 141
DO  - 10.1016/j.ijfoodmicro.2010.01.026
ER  - 

@article{
author = "Šmigić, Nada and Rajković, Andreja and Nielsen, Dennis Sandris and Arneborg, Nils and Siegumfeldt, Henrik and Devlieghere, Frank",
year = "2010",
abstract = "As mild decontamination treatments are gaining more and more interest due to increased consumer demands for fresh foods, it is of great importance to establish the influence of decontamination treatments on the subsequent bacterial behaviour under suboptimal storage conditions. For this purpose Campylobacter jejuni cells treated with lactic acid (LA, 3% lactic acid, pH 4.0, 2 min) or chlorine dioxide (ClO2, 20 ppm, 2 min) were inoculated in Bolton broth (pH 6.0) and incubated under 80% O-2/20% N-2, 80% CO2/20% N-2, air or micro-aerophilic (10% CO2/85% N-2/5% O-2) atmosphere, at 4 degrees C during 7 days. Treatment with water served as a control. The most suppressive atmosphere for the survival of C jejuni was O-2-rich atmosphere, followed by air, micro-aerophilic and CO2-rich atmosphere. The survival of C. jejuni was dependent on the type of initial decontamination treatment, with water treated cells showing the greatest survival followed by LA and ClO2 treated cells. Intracellular pH (pH(i)) of individual C. jejuni cells was determined using Fluorescence Ratio Imaging Microscopy (FRIM). At all tested conditions, different subpopulation of the cells could be distinguished based on their pH(i) values. The pH(i) response was independent on the surrounding atmosphere since similar distribution of the subpopulations was observed for all tested atmospheres. However, the pH(i) response was dependent on the initial decontamination treatment. The investigation of intracellular parameters gave an insight into pathogen behaviour under stressful conditions at intracellular level. The results obtained in this study highlighted the importance of combining decontamination technologies with subsequent preservation techniques to the control survival and growth of foodborne pathogens.",
publisher = "Elsevier, Amsterdam",
journal = "International Journal of Food Microbiology",
title = "Survival of lactic acid and chlorine dioxide treated Campylobacter jejuni under suboptimal conditions of pH, temperature and modified atmosphere",
pages = "S146-S140",
volume = "141",
doi = "10.1016/j.ijfoodmicro.2010.01.026"
}

Šmigić, N., Rajković, A., Nielsen, D. S., Arneborg, N., Siegumfeldt, H.,& Devlieghere, F.. (2010). Survival of lactic acid and chlorine dioxide treated Campylobacter jejuni under suboptimal conditions of pH, temperature and modified atmosphere. in International Journal of Food Microbiology
Elsevier, Amsterdam., 141, S140-S146.
https://doi.org/10.1016/j.ijfoodmicro.2010.01.026

Šmigić N, Rajković A, Nielsen DS, Arneborg N, Siegumfeldt H, Devlieghere F. Survival of lactic acid and chlorine dioxide treated Campylobacter jejuni under suboptimal conditions of pH, temperature and modified atmosphere. in International Journal of Food Microbiology. 2010;141:S140-S146.
doi:10.1016/j.ijfoodmicro.2010.01.026 .

Šmigić, Nada, Rajković, Andreja, Nielsen, Dennis Sandris, Arneborg, Nils, Siegumfeldt, Henrik, Devlieghere, Frank, "Survival of lactic acid and chlorine dioxide treated Campylobacter jejuni under suboptimal conditions of pH, temperature and modified atmosphere" in International Journal of Food Microbiology, 141 (2010):S140-S146,
https://doi.org/10.1016/j.ijfoodmicro.2010.01.026 . .

TY  - JOUR
AU  - Šmigić, Nada
AU  - Rajković, Andreja
AU  - Nielsen, Dennis Sandris
AU  - Siegumfeldt, Henrik
AU  - Uyttendaele, Mieke
AU  - Devlieghere, Frank
AU  - Arneborg, Nils
PY  - 2009
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/2071
AB  - The aim of the study was to determine intracellular pH (pH(i)) as an indicator of the physiological state of two Campylobacter jejuni strains (603 and 608) at the single cell level after bactericidal treatment with lactic acid (3% v/v lactic acid, pH 4.0, 0.85% w/v NaCl) and during recovery and survival using Fluorescence Ratio Imaging Microscopy (FRIM). After exposure to lactic acid solution a decline in pHi to 5.5 (FRIM detection limit) was observed in the majority of cells (75-100%) within 2 min. The enumeration data revealed that after 2 min of lactic acid exposure, approx. 90% of the initial population became unculturable. In the following 10 min of exposure, a further decrease in the cell count was observed resulting in 3.53 and 3.21 log CFU/ml reduction of culturable cells at the end of the treatment. On the contrary, the FRIM results revealed that the subpopulations with pH(i >)5.5 increased between 2 and 12 min of exposure to lactic acid. Removing the acid stress and incubating the cells suspension under the more favourable conditions resulted in an immediate increase in cell population with pH(i)> pH(ex) for both C. jejuni strains. Further 24 h incubation at 37 degrees C resulted in increased pHi and colony count (recovery study). On the contrary, 24 h incubation at suboptimal temperature of 4 degrees C, showed pHi decrease to pH(ex)=6.0 (no pH gradient) in the whole population of C. jejuni cells. Rather than dying, cells exposed for longer time (72 and 120 h) to 4 degrees C increased the subpopulation of the cells with positive pH gradient, mostly comprised of the cells with Delta pH > 0.5, indicating the ability of C. jejuni cells to regulate their metabolic activity under suboptimal conditions.
PB  - Elsevier, Amsterdam
T2  - International Journal of Food Microbiology
T1  - Intracellular pH as an indicator of viability and resuscitation of Campylobacter jejuni after decontamination with lactic acid
EP  - 143
IS  - 2
SP  - 136
VL  - 135
DO  - 10.1016/j.ijfoodmicro.2009.07.023
ER  - 

@article{
author = "Šmigić, Nada and Rajković, Andreja and Nielsen, Dennis Sandris and Siegumfeldt, Henrik and Uyttendaele, Mieke and Devlieghere, Frank and Arneborg, Nils",
year = "2009",
abstract = "The aim of the study was to determine intracellular pH (pH(i)) as an indicator of the physiological state of two Campylobacter jejuni strains (603 and 608) at the single cell level after bactericidal treatment with lactic acid (3% v/v lactic acid, pH 4.0, 0.85% w/v NaCl) and during recovery and survival using Fluorescence Ratio Imaging Microscopy (FRIM). After exposure to lactic acid solution a decline in pHi to 5.5 (FRIM detection limit) was observed in the majority of cells (75-100%) within 2 min. The enumeration data revealed that after 2 min of lactic acid exposure, approx. 90% of the initial population became unculturable. In the following 10 min of exposure, a further decrease in the cell count was observed resulting in 3.53 and 3.21 log CFU/ml reduction of culturable cells at the end of the treatment. On the contrary, the FRIM results revealed that the subpopulations with pH(i >)5.5 increased between 2 and 12 min of exposure to lactic acid. Removing the acid stress and incubating the cells suspension under the more favourable conditions resulted in an immediate increase in cell population with pH(i)> pH(ex) for both C. jejuni strains. Further 24 h incubation at 37 degrees C resulted in increased pHi and colony count (recovery study). On the contrary, 24 h incubation at suboptimal temperature of 4 degrees C, showed pHi decrease to pH(ex)=6.0 (no pH gradient) in the whole population of C. jejuni cells. Rather than dying, cells exposed for longer time (72 and 120 h) to 4 degrees C increased the subpopulation of the cells with positive pH gradient, mostly comprised of the cells with Delta pH > 0.5, indicating the ability of C. jejuni cells to regulate their metabolic activity under suboptimal conditions.",
publisher = "Elsevier, Amsterdam",
journal = "International Journal of Food Microbiology",
title = "Intracellular pH as an indicator of viability and resuscitation of Campylobacter jejuni after decontamination with lactic acid",
pages = "143-136",
number = "2",
volume = "135",
doi = "10.1016/j.ijfoodmicro.2009.07.023"
}

Šmigić, N., Rajković, A., Nielsen, D. S., Siegumfeldt, H., Uyttendaele, M., Devlieghere, F.,& Arneborg, N.. (2009). Intracellular pH as an indicator of viability and resuscitation of Campylobacter jejuni after decontamination with lactic acid. in International Journal of Food Microbiology
Elsevier, Amsterdam., 135(2), 136-143.
https://doi.org/10.1016/j.ijfoodmicro.2009.07.023

Šmigić N, Rajković A, Nielsen DS, Siegumfeldt H, Uyttendaele M, Devlieghere F, Arneborg N. Intracellular pH as an indicator of viability and resuscitation of Campylobacter jejuni after decontamination with lactic acid. in International Journal of Food Microbiology. 2009;135(2):136-143.
doi:10.1016/j.ijfoodmicro.2009.07.023 .

Šmigić, Nada, Rajković, Andreja, Nielsen, Dennis Sandris, Siegumfeldt, Henrik, Uyttendaele, Mieke, Devlieghere, Frank, Arneborg, Nils, "Intracellular pH as an indicator of viability and resuscitation of Campylobacter jejuni after decontamination with lactic acid" in International Journal of Food Microbiology, 135, no. 2 (2009):136-143,
https://doi.org/10.1016/j.ijfoodmicro.2009.07.023 . .