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Amino acids are the basic unit of the building blocks of proteins, and has a very wide range of applications in the fields of medicine, food, chemicals, animal husbandry and agriculture, in which L-tryptophan (L-Trp) as one of the eight essential amino acids, amino acid infusion, oral amino acids necessary for the preparation of the ingredients. Due to the rapid development of feed industry at home and abroad, as well as expanding the uses of L-tryptophan in the pharmaceutical industry, and the country is not yet large-scale production, thus making it a good prospects for development on an international market, domestic market demand products. Due to the rapid development of genetic engineering, high yield by way of genetic engineering to construct tryptophan strains to be an effective way of the production of tryptophan. Enzymes gene by the synthetic tryptophan E, D, C, B, A, head-to-tail tandem arrangement composed of the structural gene group, by its upstream promoter P trp and operon σ regulation, regulating gene the trpR the position away from the PO-structural gene group, by PCR method from coli K-12 were obtained two tryptophan operon fragment, were retained and did not retain their own promoter sequences, These two DNA fragments were cloned into the T vector, and its nucleotide sequence reported exactly the same after the sequencing. Two fragments were then cloned into the expression vector pBV220 and pET22b () to go, in accordance with the respective different promoter-induced expression were induced, and the anthranilate synthase and tryptophan synthase activity was measured by analysis with its own promoter and cloned into pET22b () expression vector a situation better, therefore selected as the transformation of the object, attenuator gene mutations by site-directed mutagenesis internal two adjacent tryptophan codon, thereby improving the manipulation sub within each amount of expression of the enzyme and enzyme activity. The article mainly through Cloning and expression of the tryptophan operon as a whole and improve the copy number of the respective enzyme genes in the tryptophan operon, and thus enhance their enzymatic activity to enhance the effect of tryptophan Yield, and compared tryptophyl the impact of the presence or absence of acid operon promoter gene expression as a whole, through the selection of different expression vectors, analysis and comparison of different intensity exogenous promoter tryptophan tryptophan operon expression, and the final selection of one of the best case, the attenuator part on tryptophan own promoter directed mutagenesis, by changing the way of its secondary structure reduces its repressor effect on the expression of the entire gene, thereby enhancing the expression levels and activity of the enzyme. L-tryptophan biosynthesis long, complex regulation, and therefore its production adjustment has been affected, there are many difficulties to build high-yield tryptophan engineered bacteria linked through genetic engineering and metabolic engineering needs from
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