Notice of RetractionThe Role of Listeria monocytogenes sigmaB and PrfA in the Expression of Bile Salt Hydrolase Gene bsh

Notice of Retraction

After careful and considered review of the content of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE´s Publication Principles.

We hereby retract the content of this paper. Reasonable effort should be made to remove all past references to this paper.

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Bile salt hydrolase in Listeria monocytogenes is only encoded by bsh gene. It plays an important role in hydrolyzing heavy concentration of bile salt when L. monocytogenes in the hypoxemic condition and is propitious to L. monocytogenes surviving in the host cell. There are complete SigB and PrfA binding sites in bsh promoter: PrfA-box(TTAAAAATTTTT AA) , SigB-box (GTTT-N15-GGGTAC). In order to investigate the role of SigB (σ^B) and PrfA in regulating bsh expression, we used RT-PCR method to analyze the bsh expression level in the four strains: L. monocytogenes EGD, EGD_ΔprfA, EGD_ΔsiB and EGD_ΔprfAΔsigB. The results were shown that σ^B and PrfA were both contribute to bsh expression, but the deletion of sigB would remarkably decrease the bsh expression, indicating σ^B was more important than PrfA in resistance of bile salt environment in gastrointestinal tract. This work will provide the theory evidence on the regulation mechanisms of virulence gene in gastrointestinal tract.