Degree
Doctor of Philosophy (PhD)
Department
School of Nutrition and Food Sciences
Document Type
Dissertation
Abstract
Healthy cattle serve as a reservoir for Escherichia coli O157:H7. This microorganism survives through the high acidity in the abomasum of the cow's stomach and may develop resistance to acidic conditions. This pathogen’s survival and adaptation under various stress and environmental conditions present significant challenges to food safety and potentially influence its response to subsequent stress conditions. These studies investigated the survival and stress response of E. coli O157:H7 in the stomach contents (rumen, reticulum, omasum and abomasum) of grain and grass-fed cattle. Additionally, we examined the survival and stress response during thermal processing and studied its persistence in raw manure under the environmental conditions of Louisiana. The results indicated that the E. coli O157:H7 counts significantly increased (PE. coli O157:H7 (pre-exposed to pH 4) persisted for up to 120 days with only a ~3 Log reduction, maintaining higher counts compared to bacteria adapted to pH 7 and 5. These studies highlighted the adaptive strategies of E. coli O157:H7, suggesting that its ability to withstand multiple stressors contributes significantly to its persistence and necessitates targeted control measures in agricultural and food processing environments
Date
4-22-2025
Recommended Citation
Aryal, Jyoti, "Survival and stress adaptation of Escherichia coli O157:H7 in cattle stomach contents, thermal processing, and agricultural environment" (2025). LSU Doctoral Dissertations. 6784.
https://repository.lsu.edu/gradschool_dissertations/6784
Committee Chair
Achyut Adhikari