Attachment strength and on-farm die-off rate of Escherichia coli on watermelon surfaces

Authors

Vijay Singh Chhetri
Kathryn Fontenot
Ronald Strahan
Veerachandra K. Yemmireddy, The University of Texas Rio Grande ValleyFollow
Cameron Cason
Karuna Kharel
Achyut Adhikari

Document Type

Article

Publication Date

1-8-2019

Abstract

Pre-harvest contamination of produce has been a major food safety focus. Insight into the behavior of enteric pathogens on produce in pre-harvest conditions will aid in developing pre-harvest and post-harvest risk management strategies. In this study, the attachment strength (SR) and die-off rate of E. coli on the surface of watermelon fruits and the efficacy of aqueous chlorine treatment against strongly attached E. coli population were investigated. Watermelon seedlings were transplanted into eighteen plots. Prior to harvesting, a cocktail of generic E. coli (ATCC 23716, 25922 and 11775) was inoculated on the surface of the watermelon fruits (n = 162) and the attachment strength (SR) values and the daily die-off rates were examined up to 6 days by attachment assay. After 120 h, watermelon samples were treated with aqueous chlorine (150 ppm free chlorine for 3 min). The SR value of the E. coli cells on watermelon surfaces significantly increased (PSR values, up to 120 h. The daily die-off rate of E. coli ranged from -0.12 to 1.3 log CFU/cm2. The chlorine treatment reduced the E. coli level by 4.2 log CFU/cm2 (initial level 5.6 log CFU/cm2) and 0.62 log CFU/cm2 (initial level 1.8 log CFU/cm2), on the watermelons that had an attachment time of 30 min and 120 h respectively. Overall, our findings revealed that the population of E. coli on watermelon surfaces declined over time in an agricultural environment. Microbial contamination during pre-harvest stages may promote the formation of strongly attached cells on the produce surfaces, which could influence the efficacy of post-harvest washing and sanitation techniques.

Comments

© 2019 Chhetri et al.

Recommended Citation

Chhetri VS, Fontenot K, Strahan R, Yemmireddy VK, Cason C, Kharel K, et al. (2019) Attachment strength and on-farm die-off rate of Escherichia coli on watermelon surfaces. PLoS ONE 14(1): e0210115. https://doi.org/10.1371/journal.pone.0210115

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Publication Title

PLoS ONE

DOI

10.1371/journal.pone.0210115