RESUMEN
To construct knockout vectors containing ampicillin resistant gene and partial sequence of hyaluronidase gene(Hyl)so that Hyl can be knock out by transforming the plasmid into Streptococcus zoopidemics mutans.First,partial sequence of Hyl(Hyl-1)was cloned into the vector of pMD19-T by using DNA of Streptococcus zoopidemics as template,and then a knockout vector pMD19T-SA was constructed,in which Hyl-1 gene was disrupted by inserting ampicillin resistant gene(Amp)from reverse PCR.As expected,the vector was proved to be consisted of Hyl-1-Amp-Hyl-1-pMD19-T.Thereafter,DNA fragment of Hyl-1-Amp-Hyl-1 was subcloned into pBR322 vector,the resulting construct was then checked by PCR and restriction analysis for the proper configuration of the knockout vector pBR322-SA.Both of the knockout vectors were used to transform Streptococcus zoopidemics and one recombinant was obtained in result.From results of PCR and Hyl activity assay,it was indicated that in the recombinant the Hyl gene was disrupted completely.