Cloning and molecular characteristics of enterotoxin B gene from wild staphylococcus aureus strain

  Objective   To clone the enterotox in B gene from a wild stap hylococcus aureus strain S407030, and to analyze its molecular character istics.

  Methods   The Staphylococcal enterotoxin B gene was amplified using PCR mehtod, and ligated with the pMD-18T plasmid to construct the recombinant rpMD-SEB, Which was transformed into E.coli DH5A.The positive bacteria clones were identifiedty PCR and double enzymes dieg est ion methods.The inserted SEB gene fragment was finally sequenced and its deduced SEB protein secondary structure analyzed.

  Results   705 bp SEB gene fragement was correctly cloned.Compared with S.aureus strain S6, the overall nucleo tides identity was 98.4%.Among the 11 differ ent nucleotids, 4 nucleotids leading to the encoding aminor esidues different.Ho wever, the heterog eneity of nucleotides had no significant influence on the deduced SEB protein secondary structures between the S.aureus strain S407030 and S6.

  Conclusion   The Staphylococcal Enterotox in B gene of S.aureus strain S407030 was successfully cloned, and it was relatively conserved among different S.aureus strains.The problem that the heterog eneity of nucleotides of SEB gene lead to the variety of SEB virulence deserved further study.