Main content

A study on the effect of environmental stress on the survival and subsequent lag time of Escherichia coli O157: H7

Show full item record

Title: A study on the effect of environmental stress on the survival and subsequent lag time of Escherichia coli O157: H7
Author: Li, Yaqin
Department: Department of Food Science
Advisor: Odumeru, Joseph
Abstract: The objectives of this study are (i) to determine the effect of environmental stress such as low pH on the survival of lineage I and lineage II isolates 'Escherichia coli' O157:H7 and (ii) to investigate the effect of starvation, acid and heat on the distribution of individual lag time ([tau]) of 'E. coli' O157:H7. Results showed that the survival of non-acid adapted lineage II isolates was significantly higher (P < 0.05) than that of lineage I isolates either at room temperature or 4°C in acid TSB (pH3.5) or at 37°C in synthetic gastric fluid (SGF, pH 2.5). However, following acid adaptation, the difference in the survival rate of the two lineages in SGF at 37°C was not significant (P > 0.05). Both the mean and standard deviation of [tau] value increased with the duration of stresses tested. The distributions of [tau] could be described as PearsonV, PearsonVI, Extreme Value, Lognormal, Lognorm(2), and InverseGaussian. These were the top 6 ranked distributions among the 21 types of continuous distribution available in Bestfit. However, the rank order of these distributions varied with the duration of stress treatments. Extreme Value tends to be ranked the 1st for the most severely stressed cells. Overall, Lognormal appears to be the most appropriate to characterize individual cell [tau]. When acid challenged, the more acid tolerant the strain, the less injury occurs in cells, and the shorter the subsequent lag times are.
Date: 2004
Terms of Use: All items in the Atrium are protected by copyright with all rights reserved unless otherwise indicated.

Files in this item

Files Size Format View
Li_Yaqin_MSc.pdf 5.497Mb PDF View/Open

This item appears in the following Collection(s)

Show full item record

The library is committed to ensuring that members of our user community with disabilities have equal access to our services and resources and that their dignity and independence is always respected. If you encounter a barrier and/or need an alternate format, please fill out our Library Print and Multimedia Alternate-Format Request Form. Contact us if you’d like to provide feedback:  (email address)