Characterization of rsmC as a potential reference gene for Salmonella Typhimurium gene expression during growth in spent media

Spent media is nutritionally exhausted media due to extensive previous growth of bacteria species and is known to influence the gene expression patterns of Salmonella Typhimurium in in vivo and in vitro environments. Comparative CT-based real time quantitative polymerase chain reaction (RT-PCR) requires a baseline reference gene whose expression is stable throughout experimental conditions. The normalization to a baseline gene is necessary to eliminate sample-to-sample variations of the RNA isolation and reverse transcription steps. The current study explores the suitability of rsmC to serve as a reference gene in RT-PCR gene expression quantification of S. Typhimurium during growth in spent media. In our study, although the growth range response of S. Typhimurium as measured either by optical density or colony forming units (CFU) over time in rich and spent media was significantly different, the expression of rsmC remained constant when evaluated by the corresponding CT values. rsmC could be successfully used as a reference gene in the comparative CT RT-PCR method to quantify S. Typhimurium gene expression throughout the growth range response to this nutritionally limited environment.