Joel Maki, Randy Ortiz
Escherichia coli O157:H7 (O157) remains a significant food safety concern, with cattle serving as its primary reservoir. Advancing our understanding of how O157 colonizes the bovine gut is essential for identifying the chemical and biological factors that enable successful colonization and for developing targeted preharvest interventions. Upon entering the cattle intestine, O157 is consistently exposed to both bile and oxygen, indicating that these factors may influence its colonization strategy. Here, we exposed a strain of O157 to whole bovine bile powder and oxygen, both individually and in combination. Exposure to oxygen enhanced O157 biofilm formation and upregulated genes involved in adherence to bovine intestinal cells. Exposure to bovine bile stimulated metabolic pathways that allow O157 to utilize mucus‑derived sugars, abundant nutrient sources in the cattle intestine. Together, these results demonstrate that bovine bile and oxygen each modulate O157 colonization mechanisms, positioning both as critical environmental cues that shape bacterial behavior in the cattle gut. This repository contains the partially analyzed data and code for this project.