Isolating And Identifying Of A Thermophilic XZ2K2 And Expression Of Its Cloned Dextransucrase Gene

Glucan ( Dextran ) is a physiologically and commercially important Extracellular polysaccharides. It has been widely used in indusries of medicament, food processing. Besides these application, it has a wonderful prospect of application potential in powder producing, chemical industries, metal mill running, as well as basic research.A thermostable Glucan producing strain, named XZ2K2, was isolated from samples of the conduit in the Xiang Zhou of Guangxi. On the basis of morphological observation and the analysis of the 16S rDNA sequence, XZ2K2 was identified as Thermus gemus. A 4.5kb fragment which homologous to dex gene encoding Glucan was amplified by constructing genomic library and PCR, using conservative sequence of dex gene as primers. The 4.5kb fragment was sequenced. A open reading frame (ORF) encoded amino acids was identified from this fragment and was shared 90% homology with reported dex gene. One recombinant plssmid, named pSE380-dex was obtained by ligatied the 4.5kb fragment with pSE380 vector and transformated into E.coli strains JM109. It was shown that this dex gene can express in E.coli strains JM109.