Transcriptomic consequence of the mutation in the response regulator gene gacA of the two-component regulatory system GacS/GacA in the rhizosphere biocontrol strain Pseudomonas aeruginosa M18

To investigate the influence of GacA on the genome-wide transcription of the rhizobacterium P. aeruginosa M18, DNA microarray experiments were carried out to compare the transcriptional profile of M18 with that of the gacA mutant grown to the early stationary phase (OD600 = 5.0 ~ 5.5) in KMB media. When compared with the M18 parental strain, the transcriptomic profile of gacA mutant revealed the significantly differential expression (increased or decreased by at least 2-fold as well as p-value < 0.05) of 839 genes, which represent approximately 15% of all 5696 annotated genes in the M18 genome. Of these 839 genes, 472 were downregulated and 367 genes were upregulated by the gacA mutation. P. aeruginosa M18 and its gacA mutant were grown to OD600=5.0-5.5 (early stationary phase) in KMB medium at 28℃. Three independent experiments were performed at each time.