Gastrointestinal signals in supplemented media reveal a role in adherence for the autotransporter gene.

causes severe diarrheal disease worldwide. While many aspects of pathogenesis have been elucidated, significant knowledge gaps remain regarding the role of putative chromosomally-encoded virulence genes. The uncharacterized gene encoded on the chromosome has significant nucleotide sequence identity to the fluffy () antigen 43 autotransporter gene in pathogenic . Here, we constructed a Δ mutant in strain 2457T and examined the effects of this mutation on bacterial cell aggregation, biofilm formation, and adherence to colonic epithelial cells. Analyses included the use of growth media supplemented with glucose and bile salts to replicate small intestinal signals encountered by . Deletion of the gene in 2457T affected epithelial cell adherence, resulted in quicker bacterial cell aggregation, but did not affect biofilm formation. This work highlights a functional role for the gene in pathogenesis and further demonstrates the importance of using relevant and appropriate gastrointestinal signals to characterize virulence genes of enteropathogenic bacteria.