Evaluation of three reference genes of Escherichia coli for mRNA expression level normalization in view of salt and organic acid stress exposure in food.
Escherichia coli can adapt to various stress conditions encountered in food through induction of stress response genes encoding proteins that counteract the respective stresses. To understand the impact and the induction of these genes under food-associated stresses, changes in the levels of their mRNA expression in response to such stresses can be analysed. Relative quantification of mRNA levels by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) requires normalization to reference genes with stable expression under the experimental conditions being investigated. We examined the validity of three housekeeping genes (cysG, hcaT and rssA) among E. coli strains exposed to salt and organic acid stress. The rssA gene was shown to be the most stably expressed gene under such stress adaptation experimental models. The cysG gene was the least stable, whereas the hcaT gene showed similar interstrain variability as rssA but lower expression stability in the different stress adaptation models.
Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Zurich, Switzerland; Research station Agroscope Liebefeld-Posieux ALP, Bern, Switzerland.
Silvio
S
Peng
Roger
R
Stephan
Jörg
J
Hummerjohann
Taurai
T
Tasara
D002264:Carboxylic Acids / Q000633:toxicity*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D005504:Food Analysis; D020869:Gene Expression Profiling / Q000379:methods* / Q000592:standards*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D012015:Reference Standards; D012492:Salts / Q000633:toxicity*; D013312:Stress, Physiological
D002264:Carboxylic Acids; D012492:Salts
RT-qPCR; gene expression; organic acid stress; reference gene; salt stress; stress response