Objective This study is to verify the use of rich BHI medium to substitute synthetic media for gene regulation studies in Yersinia pestis. Methods The transcriptional regulation of rovA by PhoP or via temperature upshift, and that of pla by CRP were investigated when Y. pestis was cultured in BHI. After cultivation under 26 ~C, and with temperature shifting from 26 to 37 ~C, the wild-type （WT） strain or its phoP or crp null mutant （AphoP or Acrp, respectively） was subject to RNA isolation, and then the promoter activity of rovA or plo in the above strains was detected by the primer extension assay. The rovA promoter-proximal region was cloned into the pRW50 containing a promoterless lacZ gene. The recombinant LacZ reporter plasmid was transformed into WT and AphoP to measure the promoter activity of rovA in these two strains with the ^-Galactosidase enzyme assay system. Results When Y. pestis was cultured in BHI, the transcription of rovA was inhibited by PhoP and upon temperature upshift while that ofpla was stimulated by CRP. Conclusion The rich BHI medium without the need for modification to be introduced into the relevant stimulating conditions （which are essential to triggering relevant gene regulatory cascades）, can be used in lieu of synthetic TMH media to cultivate Y. pestis for gene regulation studies.
ZHANG Yi QuanMA Li ZhiWANG LiGAO HeTAN Ya FangGUO Zhao BiaoQIU Jing FuYANG Rui FuZHOU Dong Sheng
