Transcriptomic profiling of Salmonella during lag, exponential and stationary phases of growth

Transcriptional profiles during all phases of growth of Salmonella Typhimurium SL1344 were obtained and used to investigate growth phase-dependent alterations in gene expression. Viable count growth curve analysis of the growth system showed a culture lag time of 2.09 hours, and profiles at 4, 20, 40, 60, 90 and 120 minutes were measured accordingly. For comparison, profiles of the inoculum (0 min), mid-exponential (380 min), late-exponential (630 min), early-stationary (900 min) and late-stationary phase (2880 min) were also obtained. Large-scale gene-expression changes were seen, with substantial changes within 4 minutes of inoculation, indicating the speed and sophistication at which Salmonella senses its new environment during lag phase. Timecourse; 46 samples (11 timepoints, each with two biological replicates and at least two technical replicates); each sample hybridised in a two-channel hybridization against Salmonella genomic DNA as the comparator/reference, which also acted as a control for spot quality.