Expression data from Pseudomonas aeruginosa +/- 1% ethanol

Pseudomonas aeruginosa frequently resides among ethanol-producing microbes, making its response to these microbially-produced concentrations of ethanol relevant to understanding its biology. Transcriptome analysis found that the genes involved in trehalose metabolism were induced by low concentrations of ethanol, and levels of intracellular trehalose increased significantly upon growth with ethanol. The increase in trehalose was dependent on the TreYZ pathway, and not other trehalose metabolic enzymes TreS or TreA. The sigma factor AlgU (AlgT), a homolog of RpoE in other species, was required for increased expression of the treZ gene and trehalose levels, but induction was not controlled by the well-characterized proteolysis of its antisigma factor MucA. Growth with ethanol led to increased (p)ppGpp, synthesized by SpoT, and genetic data suggest that increased (p)ppGpp stimulates AlgU-dependent transcription of treZ and other AlgU-regulated genes through DksA, a (p)ppGpp and RNA polymerase binding protein. Ethanol stimulation of trehalose also required acylhomoserine lactone (AHL)-mediated quorum sensing, as induction was not observed in a ∆lasR∆rhlR strain. A network analysis of publicly available P. aeruginosa transcriptome datasets using eADAGE provided strong support for our model that treZ and co-regulated genes are controlled by both AlgU and AHL-mediated QS. Consistent with (p)ppGpp and AHL-mediated quorum sensing regulation, ethanol, even when added at the time of culture inoculation, only stimulated treZ transcript levels and trehalose production in post-exponential phase cultures. These data highlight the integration of growth and cell density cues in responses to ethanol. We sought to understand the expression profile of wild type Pseudomonas aeruginosa (PA14) in response to growth in the presence of 1% ethanol. We harvested RNA for analysis from colony biofilms grown for 16 h at 37C on tryptone agar plates (1.5% agar) grown without (CTRL) and with (EtOH) 1% ethanol added to the molten agar. We collected duplicate samples of each condition (CTRL and EtOH) for expression analysis.