Prolonged CBD Exposure Is Associated with Higher Expression of flgA in Salmonella Typhimurium

Background/Objectives: Salmonella Typhimurium is a Gram-negative foodborne pathogen that remains a major public-health concern. In this study, we examined whether prolonged exposure to cannabidiol (CBD) was associated with altered flgA expression and related phenotypes in a laboratory-derived CBD-adapted strain compared with its susceptible parental strain. Methods: We assessed relative flgA mRNA expression, motility, growth at different pH conditions, responses to nutrient starvation, and biofilm formation. Results: The CBD-adapted strain showed approximately sixfold higher flgA mRNA expression and greater motility at pH 7. However, the pH findings were mixed: neither strain showed measurable migration at pH 3, the limited migration observed for the adapted strain at pH 12 was highly variable, and both strains showed reduced growth at extreme pH. Under nutrient starvation, relative OD600 declined in both strains, with a faster decline in the CBD-adapted strain under several CBD conditions. Biofilm measurements also differed by strain, CBD concentration, and incubation time. Conclusions: These findings show an association between prolonged CBD exposure, higher flgA expression, and altered phenotypes, but they do not establish that flgA caused the observed changes. The study therefore provides an exploratory basis for targeted genetic and phenotypic validation of CBD adaptation in Salmonella Typhimurium. Because the repeated measurements were technical replicates rather than independent biological replicates, the findings are descriptive and limited to the two strains examined.