Recombinant bacterium capable of producing L-homoserine at high yield as well as preparation method and application of recombinant bacterium

Abstract

The invention discloses a recombinant bacterium capable of producing L-homoserine at high yield as well as a preparation method and application of the recombinant bacterium. The recombinant bacterium provided by the invention is obtained by transforming the following two ways A) and B) in a chassis host bacterium: A) a metabolic way from fumaric acid to aspartic acid in the chassis host bacterium is enhanced, so that the metabolic flow of the two ways from oxaloacetic acid to L-aspartic acid and the metabolic flow of the two ways from fumaric acid to L-aspartic acid are matched in a ratio of 1: 1; and B) a metabolic pathway from aspartic acid to homoserine in the chassis host bacteria is enhanced; The method has the following advantages: 1, the iclR gene is knocked out; 2, an L-homoserine efflux pump gene rthB is used; and 3, two synthesis routes of L-aspartic acid, namely an oxaloacetic acid OAA synthesis route and a fumaric acid FUM synthesis route, are accurately regulated and controlled, so that the two synthesis fluxes are matched in a ratio of 1: 1, the reduction force balance in the fermentation process of the L-homoserine is realized, and the yield of the L-homoserine is maximized.

Description

technical field [0001] The invention belongs to the field of biotechnology, and in particular relates to a recombinant bacterium with high production of L-homoserine and its preparation method and application. Background technique [0002] L-homoserine (L-homoserine) is a naturally occurring non-protein amino acid, which exists in a small amount in many species as a common intermediate in the biosynthesis of threonine, methionine and lysine. Since L-homoserine has an L-type-α amino acid basic skeleton, and its γ-hydroxyl has various chemical activities, L-homoserine and its derivatives have important applications in pharmaceuticals and physiology as pharmaceutical intermediates. prospect. As a precursor of threonine, homoserine has similarities in the transformation of metabolic pathways. [0003] At present, there are mainly three methods for producing L-homoserine at home and abroad: chemical method, enzyme catalysis and microbial fermentation. The chemical method is un...

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Problems solved by technology

The chemical method is unfriendly to the environment and has high cost because of the use of iodide and the generation of sulfide; the enzymatic method uses pyruvate and formaldehyde to generate homoserine under the combined action of aldolase and L-amino acid dehydrogenase. The main problem of the process is still the high cost, the use of toxic raw materials formaldehyde and formic acid, and the use of expensive coenzymes, etc.; the microbial fermentation method has the advantages of low cost, mild conditions, and environmental protection, but because homoserine has an inhibitory effect on microbial growth , so there are still no reports of higher yields of homoserine at home and abroad

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