Real-time PCR used to measure stress-induced changes in the expression of the genes of the alginate pathway of Pseudomonas aeruginosa

Aims: To measure the concentration of mRNAs transcribed from four genes inv olved in alginate production using real-time PCR. Methods and Results: The mRNA concentrations in cells grown in normal and s tress conditions were compared. A difference in the expression of algD, the key gene leading to overproduction of alginate, was detected between algin ate-producing and non-alginate-producing strains grown under normal conditi ons. After growth on 3% ethanol (known to stimulate alginate production), b ut not after heat-shock, an increase in algD mRNA levels and a correspondin g decrease in mucB (a regulatory gene) mRNA levels were detected in all str ains. Conclusions: The quantitative results suggest that the mucB gene may have a role in recognition of stress conditions, and that having a disrupted mucA gene does not always result in a mucoid phenotype. Significance and Impact of the Study: Real-time PCR can be used to quantify mRNA and is a convenient method of analysing bacterial gene expression.