Abstract：Objective: To investigate whether the expression of mig-14 in Salmonellaenterica serovar Typhi(S. Typhi) depends on Fis, OmpR, IHF and HilD in the bacteria treated with polymyxin B(PB). Methods: The homologous recombination mediated by suicide plasmid was used to knock out hilD, himA, himD of S.Typhi. qRT-PCR and lacZ fusion assay were used to compare the transcripitional level of mig-14 in the mutant strains(himA,himD, hilD, fis and ompR) with that of the wild-type strains of S. Typhi to identify the regulators of mig-14. Results: The hilD, himA and himD deletion mutants of S. Typhi were successfully constructed. The qRT-PCR results showed that when treated with PB, mRNA levels of mig-14 were significantly reduced in fis, ompR, hilD, himA and himD mutant strains compared with the wild-type strains. The results of lacZ fusion assay indicated that the promoter activities of mig-14 were also significantly decreased in fis, ompR, hilD, himA and himD mutant strains compared with the wild-type strains.Conclusion: Fis, OmpR, IHF and HilD could promote the expression of mig-14 in S. Typhi under the treatment of PB.
［Key words］Salmonella enterica serovar Typhi; polymyxin B; mig-14; gene regulation
2017, Vol. 27 
