Abstract: The separate method of producing colloid gene XanA from Xanthomonas campestris was promoted in this thesis. By the means of genetic engineering, the genetic DNA of Xanthan Gum was acted as template to obtain the gene XanA. And in the course of which, optimizing experiment of PCR analysis was made. Ultimately, the yield of Xanthan Gum is expected to increase geminately. This approach could be used to separate gene XanA rapidly. The purity of the obtained gene XanA was good enough for the establishment of genomic library and recombine plastid.

Key words: Xanthomonas campestris, genomic DNA, gene