AIM:To study the effect of integration of tandem aroG-pheAgenes into the tyrA locus of Corynebacterium glutamicum(C.glutamicum) on the production of L-phenylalanine.METHODS:By nitrosoguanidine mutagenesis,five p-fluorophenylalanine (FP)-resistant mutants of C.glutamicumFP were selected.The tyrA gene encoding prephenatedehydrogenase (PDH) of C.glutamicum was amplified bypolymerase chain reaction (PCR) and cloned on the plasmidpPR.Kanamycin resistance gene (Kin) and the P_(BF)-aroG-pheA-T (GA) fragment of pGA were inserted into tyrA geneto form targeting vectors pTK and pTGAK,respectively.Then,they were transformed into C.glutamicurn FP respectivelyby electroporation.Cultures were screened by a mediumcontaining kanamycin and detected by PCR and phenotypeanalysis.The transformed strains were used for L-phenylalaninefermentation and enzyme assays.RESULTS:Engineering strains of C.glutamicum (Tyr-) wereobtained.Compared with the original strain,the transformedstrain C.glutamicum GAK was observed to have the highestelevation of L-phenylalanine production by a 1.71-fold,and 2.9-,3.36-,and 3.0-fold in enzyme activities ofchorismate mutase,prephenate dehydratase and 3-deoxy-D-arabinoheptulosonate-7-phosphate synthase,respectively.CONCLUSION:Integration of tandem aroG-pheA genes intotyrA locus of C.glutamicum chromosome can disrupt tyrAgene and increase the yield of L-phenylalanine production. AIM: To study the effect of integration of tandem aroG-pheAgenes into the tyrA locus of Corynebacterium glutamicum (C. glutamine) on the production of L-phenylalanine. METHODS: By nitrosoguanidine mutagenesis, five p-fluorophenylalanine (FP) -resistant mutants of C. glutamicum FP were selected. The tyrA gene encoding prephenate dehydrogenase (PDH) of C. glutamicum was amplified by polymerase chain reaction (PCR) and cloned on the plasmid pPR. Kanamycin resistance gene (Kin) and the P - (BF) -aroG- pheA-T (GA) fragment of pGA were inserted into tyrA geneto form targeting vectors pTK and pTGAK, respectively. They were transformed into C. glutamicum FP respectively by electroporation. Cultures were screened by a medium containing kanamycin and detected by PCR and phenotype analysis were used for L-phenylalaninefermentation and enzyme assays .RESULTS: Engineering strain of C. glutamicum (Tyr-) wereobtained. Compared with the original strain, the transformed strain C. glutamicum GAK was obse rved to have the highestelevation of L-phenylalanine production by a 1.71-fold, and 2.9-, 3.36-, and 3.0-fold in enzyme activities ofchorismate mutase, prephenate dehydratase and 3-deoxy-D-arabinoheptulosonate-7-phosphate synthase, respectively .CONCLUSION: Integration of tandem aroG-pheA genes intotyrA locus of C. glutamicum chromosome can disrupt tyrAgene and increase the yield of L-phenylalanine production.