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Hydrophobic and electrostatic interaction chromatography for estimating changes in cell surface charge of Escherichia coli cells treated with pulsed electric fields.
Foodborne Pathog Dis. 2011 Oct; 8(10):1103-9.FP

Abstract

Pulsed electric field (PEF) treatments, a nonthermal process, have been reported to injure and inactivate bacteria in liquid foods. However, the effect of this treatment on bacterial cell surface charge and hydrophobicity has not been investigated. Apple juice (pH 3.8) purchased from a wholesale distributor was inoculated with cocktail of Escherichia coli O157:H7 at 7.4 log CFU/mL, processed with a PEF at a field strength of 18.4 kV/cm and 32.2 kV/cm at 25°C, 35°C, and 45°C with a treatment time of 160 μs and a flow rate of 120 mL/min. Bacterial cell surface charge and hydrophobicity of untreated and PEF-treated E. coli O157:H7 were determined immediately and after storage at 5°C and 23°C using hydrophobic and electrostatic interaction chromatography. Similarly, the populations surviving the PEF treatments including injured cells were determined by plating 0.1 mL of the sample on sorbitol MacConkey agar and tryptic soy agar (TSA) plates. The surviving populations of E. coli cells after PEF treatment varied depending on field strength and treatment temperature used. Percent injury in the surviving populations was high immediately after PEF treatment and varied among treatment temperatures. Cell surface charge of E. coli bacteria before PEF treatment averaged 32.10±8.12. PEF treatments at 25°C, 35°C, and 45°C reduced the above surface charge to 26.34±1.24, 14.24±3.30, and 6.72±2.82, respectively. Similarly, the surface hydrophobicity of untreated E. coli cells at 0.194±0.034 was increased to an average of 0.268±0.022, 0.320±0.124, and 0.586±0.123 after PEF treatments at 25°C, 35°C, and 45°C, respectively. The results of this study indicate that PEF treatment affects the outer cell envelope of E. coli bacteria as evidenced by the changes in surface hydrophobicity and cell surface charge leading to injury and subsequent inactivation of the cells.

Authors+Show Affiliations

Food Safety Intervention Technologies Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 East Mermaid Lane,Wyndmoor, PA 19038, USA. dike.ukuku@ars.usda.govNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

21668373

Citation

Ukuku, Dike O., et al. "Hydrophobic and Electrostatic Interaction Chromatography for Estimating Changes in Cell Surface Charge of Escherichia Coli Cells Treated With Pulsed Electric Fields." Foodborne Pathogens and Disease, vol. 8, no. 10, 2011, pp. 1103-9.
Ukuku DO, Yuk HG, Zhang H. Hydrophobic and electrostatic interaction chromatography for estimating changes in cell surface charge of Escherichia coli cells treated with pulsed electric fields. Foodborne Pathog Dis. 2011;8(10):1103-9.
Ukuku, D. O., Yuk, H. G., & Zhang, H. (2011). Hydrophobic and electrostatic interaction chromatography for estimating changes in cell surface charge of Escherichia coli cells treated with pulsed electric fields. Foodborne Pathogens and Disease, 8(10), 1103-9. https://doi.org/10.1089/fpd.2011.0911
Ukuku DO, Yuk HG, Zhang H. Hydrophobic and Electrostatic Interaction Chromatography for Estimating Changes in Cell Surface Charge of Escherichia Coli Cells Treated With Pulsed Electric Fields. Foodborne Pathog Dis. 2011;8(10):1103-9. PubMed PMID: 21668373.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Hydrophobic and electrostatic interaction chromatography for estimating changes in cell surface charge of Escherichia coli cells treated with pulsed electric fields. AU - Ukuku,Dike O, AU - Yuk,Hyun-Gyun, AU - Zhang,Howard, Y1 - 2011/06/13/ PY - 2011/6/15/entrez PY - 2011/6/15/pubmed PY - 2013/12/19/medline SP - 1103 EP - 9 JF - Foodborne pathogens and disease JO - Foodborne Pathog Dis VL - 8 IS - 10 N2 - Pulsed electric field (PEF) treatments, a nonthermal process, have been reported to injure and inactivate bacteria in liquid foods. However, the effect of this treatment on bacterial cell surface charge and hydrophobicity has not been investigated. Apple juice (pH 3.8) purchased from a wholesale distributor was inoculated with cocktail of Escherichia coli O157:H7 at 7.4 log CFU/mL, processed with a PEF at a field strength of 18.4 kV/cm and 32.2 kV/cm at 25°C, 35°C, and 45°C with a treatment time of 160 μs and a flow rate of 120 mL/min. Bacterial cell surface charge and hydrophobicity of untreated and PEF-treated E. coli O157:H7 were determined immediately and after storage at 5°C and 23°C using hydrophobic and electrostatic interaction chromatography. Similarly, the populations surviving the PEF treatments including injured cells were determined by plating 0.1 mL of the sample on sorbitol MacConkey agar and tryptic soy agar (TSA) plates. The surviving populations of E. coli cells after PEF treatment varied depending on field strength and treatment temperature used. Percent injury in the surviving populations was high immediately after PEF treatment and varied among treatment temperatures. Cell surface charge of E. coli bacteria before PEF treatment averaged 32.10±8.12. PEF treatments at 25°C, 35°C, and 45°C reduced the above surface charge to 26.34±1.24, 14.24±3.30, and 6.72±2.82, respectively. Similarly, the surface hydrophobicity of untreated E. coli cells at 0.194±0.034 was increased to an average of 0.268±0.022, 0.320±0.124, and 0.586±0.123 after PEF treatments at 25°C, 35°C, and 45°C, respectively. The results of this study indicate that PEF treatment affects the outer cell envelope of E. coli bacteria as evidenced by the changes in surface hydrophobicity and cell surface charge leading to injury and subsequent inactivation of the cells. SN - 1556-7125 UR - https://www.unboundmedicine.com/medline/citation/21668373/Hydrophobic_and_electrostatic_interaction_chromatography_for_estimating_changes_in_cell_surface_charge_of_Escherichia_coli_cells_treated_with_pulsed_electric_fields_ L2 - https://www.liebertpub.com/doi/10.1089/fpd.2011.0911?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -