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One-step of tryptophan attenuator inactivation and promoter swapping to improve the production of L-tryptophan in Escherichia coli

BACKGROUND: L-tryptophan is an aromatic amino acid widely used in the food, chemical and pharmaceutical industries. In Escherichia coli, L-tryptophan is synthesized from phosphoenolpyruvate and erythrose 4-phosphate by enzymes in the shikimate pathway and L-tryptophan branch pathway, while L-serine...

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Detalles Bibliográficos
Autores principales: Gu, Pengfei, Yang, Fan, Kang, Junhua, Wang, Qian, Qi, Qingsheng
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2012
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3311589/
https://www.ncbi.nlm.nih.gov/pubmed/22380540
http://dx.doi.org/10.1186/1475-2859-11-30
Descripción
Sumario:BACKGROUND: L-tryptophan is an aromatic amino acid widely used in the food, chemical and pharmaceutical industries. In Escherichia coli, L-tryptophan is synthesized from phosphoenolpyruvate and erythrose 4-phosphate by enzymes in the shikimate pathway and L-tryptophan branch pathway, while L-serine and phosphoribosylpyrophosphate are also involved in L-tryptophan synthesis. In order to construct a microbial strain for efficient L-tryptophan production from glucose, we developed a one step tryptophan attenuator inactivation and promoter swapping strategy for metabolic flux optimization after a base strain was obtained by overexpressing the tktA, mutated trpE and aroG genes and inactivating a series of competitive steps. RESULTS: The engineered E. coli GPT1002 with tryptophan attenuator inactivation and tryptophan operon promoter substitution exhibited 1.67 ~ 9.29 times higher transcription of tryptophan operon genes than the control GPT1001. In addition, this strain accumulated 1.70 g l(-1 )L-tryptophan after 36 h batch cultivation in 300-mL shake flask. Bioreactor fermentation experiments showed that GPT1002 could produce 10.15 g l(-1 )L-tryptophan in 48 h. CONCLUSIONS: The one step inactivating and promoter swapping is an efficient method for metabolic engineering. This method can also be applied in other bacteria.