Environmental stress modulates expression of biofilm-related genes in Salmonella

AIMS: Biofilms formed by Salmonella are a significant concern in the poultry industry due to their role in pathogen persistence. However, there is a lack of data observing the expression of biofilm related genes in different Salmonella serovars. The aim of this study was to investigate the expression patterns of key biofilm-associated genes across three Salmonella serovars, namely Salmonella Typhimurium, Kentucky, and Reading, throughout their biofilm growth cycles. METHODS AND RESULTS: The expressions of csgD, bapA, bcsA, adrA, and luxS were analyzed in cultures representing different biofilm growth phases: 12 h and 24 h planktonic cells, 4-day old biofilms, and 5-day old biofilms under nutrient deprivation. The findings from this study revealed that only S. Reading exhibited upregulation of these genes at the 24 h planktonic stage at a maximum of 9.58-fold. In contrast, a downregulation of all five genes was noted in the 4-day old biofilms for all serovars. Most notably, bapA was downregulated by 3 765-fold in S. Typhimurium. Upon subjecting the biofilms to nutrient deprivation, there was a notable recovery in the activity of these genes across all serovars with the exception of csgD in S. Typhimurium. CONCLUSION: These results suggest that expression of biofilm-associated genes is stimulated by nutrient availability even at biofilm maturity and may vary among different serovars.