Salmonella typhimurium 14028s Transposon library recovered after three consecutive rounds of growth to late log phase in M9 minimal medium (arabinose 0.4%) at 37°C with aeration, compared to an expansion of the initial library selected on Luria agar plates + kanamycin (50ug/ml), O/N at 37°C Keywords: Transposon tag analysis 2 biological replicates analysed after arbitrarily primed sampling (Klenow, DOPR degenerate primer) + specific PCR amplification (Taq DNA Pol) + T7 in vitro transcription (AmpliScribe T7) + RT labeling (Cy3) + hybridization, compared to identically processed standard library (Cy5)