BioProject

Pathogens like E. coli O157:H7 are responsible for many outbreaks and can be found and survive in poor inorganic phosphate (Pi) environments. In E. coli the phosphate homeostasis is regulated by the Pst system and the two-component system PhoB/R. In a Δpst mutant, PhoB is constitutively activated and biofilm formation is increased. To understand how PhoB activation lead to biofilm increase, we compared the transcriptomes of EDL933 the WT strain and Δpst mutant both grown in MOPS Pi rich medium, using the Affymetrix GeneChip® E. coli Genome 2.0 Array. Overall design: EDL933WT strain and its isogenic mutant Δpst were grown in Pi+ conditions until the OD600 reached respectively 0.55 to 0.6. Samples equal to 5.10e8 CFU were taken from this mid log phase and processed for transcriptomes analysis. Ten µg of RNAs were extracted and retro-transcripted. One µg of the fragmented and biotinylated cDNAs, were hybridized onto Affymetrix GeneChip® E. coli. The data were processed using the FlexArray® software; RMA normalization and the levels of transcription obtained from 3 biological replicates of each experimental condition were compared using the EB (Wright & Simon) algorithm. We then conducted comparisons between Δpst mutant and EDL933WT both grown in Pi+. The differentially expression conditions corresponded to 2-fold change (FC) cut-off and p-value < 0.05.