Flow cytometry and growth-based analysis of the effects of fruit sanitation on the physiology of Escherichia coli in orange juice

Research output: Contribution to journalArticlepeer-review

Standard

Harvard

APA

Vancouver

Author

Bibtex

@article{e771103b3a9b4abd847de5a31143cb2d,
title = "Flow cytometry and growth-based analysis of the effects of fruit sanitation on the physiology of Escherichia coli in orange juice",
abstract = "Chlorine-based solutions are commonly used to sanitize orange fruits prior to juice extraction. We used flow cytometry (FCM) to investigate the physiology of Escherichia coli following its subjection to chlorine-based solutions and alternative sanitizing agents (H2O2 and organic acids). Green fluorescent protein (GFP)-generating E. coli K-12 were washed with 50-200 ppm available chlorine (AC), 1-5% H2O2, 2-4% citric acid, 4% acetic acid or 4% lactic acid, after which they were added to 1.2 μm-filtered orange juice (OJ). Cell physiology was investigated with FCM during storage at 4 ºC, and culturability was determined using plate counting. Analysis of GFP fluorescence allowed estimation of intracellular pH (pHi). FCM results demonstrated an inverse relationship between the concentration of AC or H2O2 and cellular health in OJ. Higher concentrations of sanitizer also resulted in a significantly greater number of viable but non-culturable (VBNC) cells. Real-time FCM showed that supplementation of AC with 2% citric acid, but not with 100 ppm of Tween-80, led to a significant reduction in pHi of the cells incubated in OJ, and that the majority of the reduction in pHi occurred during the first 2 minutes of incubation in OJ. Organic acids were found to be more effective than both AC and H2O2 in reducing the pHi, viability and culturability of the cells in OJ. The results confirmed the hypothesis that consecutive subjection of E. coli to maximum legally permitted concentrations of sanitizers and OJ induces the VBNC state. Furthermore, we demonstrate successful application of FCM for monitoring the efficacy of washing procedures.",
keywords = "Escherichia coli, VBNC cells, Flow cytometry, Fruit sanitation, Orange juice",
author = "Amir Anvarian and Madeleine Smith and Timothy Overton",
year = "2019",
month = feb,
day = "7",
doi = "10.1002/fsn3.947",
language = "English",
volume = "7",
pages = "1072--1083",
journal = "Food Science and Nutrition",
issn = "2048-7177",
publisher = "John Wiley & Sons",
number = "3",

}

RIS

TY - JOUR

T1 - Flow cytometry and growth-based analysis of the effects of fruit sanitation on the physiology of Escherichia coli in orange juice

AU - Anvarian, Amir

AU - Smith, Madeleine

AU - Overton, Timothy

PY - 2019/2/7

Y1 - 2019/2/7

N2 - Chlorine-based solutions are commonly used to sanitize orange fruits prior to juice extraction. We used flow cytometry (FCM) to investigate the physiology of Escherichia coli following its subjection to chlorine-based solutions and alternative sanitizing agents (H2O2 and organic acids). Green fluorescent protein (GFP)-generating E. coli K-12 were washed with 50-200 ppm available chlorine (AC), 1-5% H2O2, 2-4% citric acid, 4% acetic acid or 4% lactic acid, after which they were added to 1.2 μm-filtered orange juice (OJ). Cell physiology was investigated with FCM during storage at 4 ºC, and culturability was determined using plate counting. Analysis of GFP fluorescence allowed estimation of intracellular pH (pHi). FCM results demonstrated an inverse relationship between the concentration of AC or H2O2 and cellular health in OJ. Higher concentrations of sanitizer also resulted in a significantly greater number of viable but non-culturable (VBNC) cells. Real-time FCM showed that supplementation of AC with 2% citric acid, but not with 100 ppm of Tween-80, led to a significant reduction in pHi of the cells incubated in OJ, and that the majority of the reduction in pHi occurred during the first 2 minutes of incubation in OJ. Organic acids were found to be more effective than both AC and H2O2 in reducing the pHi, viability and culturability of the cells in OJ. The results confirmed the hypothesis that consecutive subjection of E. coli to maximum legally permitted concentrations of sanitizers and OJ induces the VBNC state. Furthermore, we demonstrate successful application of FCM for monitoring the efficacy of washing procedures.

AB - Chlorine-based solutions are commonly used to sanitize orange fruits prior to juice extraction. We used flow cytometry (FCM) to investigate the physiology of Escherichia coli following its subjection to chlorine-based solutions and alternative sanitizing agents (H2O2 and organic acids). Green fluorescent protein (GFP)-generating E. coli K-12 were washed with 50-200 ppm available chlorine (AC), 1-5% H2O2, 2-4% citric acid, 4% acetic acid or 4% lactic acid, after which they were added to 1.2 μm-filtered orange juice (OJ). Cell physiology was investigated with FCM during storage at 4 ºC, and culturability was determined using plate counting. Analysis of GFP fluorescence allowed estimation of intracellular pH (pHi). FCM results demonstrated an inverse relationship between the concentration of AC or H2O2 and cellular health in OJ. Higher concentrations of sanitizer also resulted in a significantly greater number of viable but non-culturable (VBNC) cells. Real-time FCM showed that supplementation of AC with 2% citric acid, but not with 100 ppm of Tween-80, led to a significant reduction in pHi of the cells incubated in OJ, and that the majority of the reduction in pHi occurred during the first 2 minutes of incubation in OJ. Organic acids were found to be more effective than both AC and H2O2 in reducing the pHi, viability and culturability of the cells in OJ. The results confirmed the hypothesis that consecutive subjection of E. coli to maximum legally permitted concentrations of sanitizers and OJ induces the VBNC state. Furthermore, we demonstrate successful application of FCM for monitoring the efficacy of washing procedures.

KW - Escherichia coli

KW - VBNC cells

KW - Flow cytometry

KW - Fruit sanitation

KW - Orange juice

UR - http://www.scopus.com/inward/record.url?scp=85061284723&partnerID=8YFLogxK

U2 - 10.1002/fsn3.947

DO - 10.1002/fsn3.947

M3 - Article

C2 - 30918650

VL - 7

SP - 1072

EP - 1083

JO - Food Science and Nutrition

JF - Food Science and Nutrition

SN - 2048-7177

IS - 3

ER -