Transcription profiling of Pseudomonas aeruginosa after PCP shock

ABSTRACT: Through chemical contamination of natural environments, microbial communities are exposed to many different types of chemical stressors; however, research on whole genome responses to this contaminant stress is limited. This study examined the transcriptome response of a common soil bacterium, Pseudomonas aeruginosa, to the common environmental contaminant pentachlorophenol (PCP). Cells were grown in chemostats at a low growth rate to obtain substrate-limited, steady-state, balanced-growth conditions. The PCP stress was administered as a continuous increase in concentration, and samples taken over time were examined for physiological function changes with whole cell acetate uptake rates (WAUR) and cell viability, and for gene expression changes using Affymetrix GeneChip technology and RT-PCR. Cell viability, measured by heterotrophic plate counts, showed a moderately steady decrease after exposure to the stressor, but WAURs did not change in response to PCP. In contrast to the physiological data, the microarray data showed significant changes in the expression of several genes. In particular, genes coding for multi-drug efflux pumps, including MexAB-OprM, were strongly upregulated. The upregulation of these efflux pumps protected the cells from the potentially toxic effects of PCP, allowing the physiological whole-cell function to remain constant. Experiment Overall Design: Cells of P. aeruginosa were grown in steady-state nutrient-limiting conditions using a minimal medium with acetate as the sole carbon source. PCP was added as a continuous input, and the samples were taken at timepoints corresponding to approximately 0.5, 1, and 2 generation times. Reactors were run at least in triplicate, and samples from duplicate WT reactors and a single RpoS- reactor were used for the microarrays. Gene expression is reported as the average fold-change associated with gene expression of PCP-shocked cells compared with the pre-PCP timepoint (0 hours) for the WT.

ORGANISM(S): Pseudomonas aeruginosa

SUBMITTER: Nancy Love 

PROVIDER: E-GEOD-5604 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress