PMID: 42347Aug 1, 1979

Hyperproduction of tryptophan by Escherichia coli: genetic manipulation of the pathways leading to tryptophan formation

Applied and Environmental Microbiology
D E Tribe, J Pittard


Conversion of glucose and ammonium salts into tryptophan by mutants of Escherichia coli was examined as part of a feasibility study on the manufacture of tryptophan. This involved construction, largely by transduction, or a variety of multiple-mutation strains with defined genotypes. By comparing the properties of these strains, we were able to define in biochemical terms several changes that significantly enhance process productivity, namely (i) release of the first enzyme of the common pathway of aromatic biosynthesis and the first enzyme of the tryptophan pathway (3-deoxy-D-arabino-heptulosonate 7-phosphate synthase and the anthranilate aggregate, respectively) from inhibition by end products, (ii) blockage of the diversion of chorismate to phenylalanine and tyrosine biosynthesis, and (iii) presence of highly elevated tryptophan pathway enzyme levels, such as result from interference with both repression and attenuation, combined with gene amplification. By using strains carrying appropriate mutations to effect all of these changes, high values of specific productivity were obtained in bath culture (approximately 80 mg/g [dry weight] per h). Furthermore, a pronounced decay in the level of 3-deoxy-D-arabino-heptulosonate 7-ph...Continue Reading


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Related Concepts

Tryptophan Synthase
Biochemical Pathway
Chorismic Acid
Ammonium salts
Alkalescens-Dispar Group
Gene Amplification
Clinical Enzyme Tests (Procedure)
2-Dehydro-3-Deoxyphosphoheptonate Aldolase
Genetic Manipulation

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