Transcriptome and secretome analyses of the adaptive response of Pseudomonas aeruginosa to suboptimal growth temperature.

Pseudomonas aeruginosa is an opportunistic pathogen involved in several diseases, including cystic fibrosis and nosocomial infections. Although the behavior of this bacterium at 37 degrees C has been intensively studied, little is known about its capacity to adapt and survive at suboptimal temperatures, such as those encountered in hospitals. In this work, transcriptomic and proteomic analyses were used to identify factors that allow P. aeruginosa to become established at room temperature (close to 25 degrees C) and thus facilitate host infections. Since the virulence of this pathogen is multifactorial and dependent on the extracellular release of toxins and degradative enzymes targeted to the host by several secretory systems, the study focused on genes activated at 25 degrees C, namely, those encoding either components of the secretory machinery or secreted proteins. These observations were enhanced by 2D-PAGE analyses, which showed that the production of effectors from type I and type II secretion systems (respectively, proteases AprA and PrpL) and of a hemolysin co-regulated protein (Hcp) related to the type VI secretion system was specifically stimulated when the growth temperature was lowered from 37 to 25 degrees C. The results provide a fundamental basis for investigating the processes that allow P. aeruginosa to adapt to suboptimal growth temperatures and which thereby promote nosocomial infection.