Method for producing L-threonine by adopting bacterial fermentation with changed aconitase controlling element

Abstract

The invention provides a method for fermentatively producing l-threonine, which comprises transforming the wild-type regulatory element of the acnA gene on the bacterial chromosome so that the expression level of aconitase A is reduced but not eliminated; and, using the transformed bacterium Fermentation produces l-threonine. In addition, the present invention also provides methods and applications derived from this method, as well as bacteria and the like that can be used in these methods and applications.

Description

Technical field [0001] The present invention is the field of amino acid fermentation. Specifically, the method and application and application of the invention involving the production of L-Suspeline and its derivatives, and bacteria that can be used in these methods and applications. Background technique [0002] The production of L-Suspeline has been industrialized through the fermentation of L-Suspamic bacteria (eg, E. Bacillus and rod bacteria of Ectophytes and Bacteria) of Elix.These bacteria can be a bacteria separated from the nature, or the bacteria obtained by mutagneity or genetic engineering transformation, or both.In the current literature report, the attention of genetic engineering transformation is mainly concentrated Akiii, ThRR In terms of genes (see the Chinese patent 94102007 and 99121353, etc.), you have not seen the 乌 乌 acid enzyme (such as, eurinase A) and its coding genes for the production of L-Soticine. [0003] Our headic acid enzyme is an enzyme in a tr...

AI Technical Summary

Problems solved by technology

It is currently known that in Escherichia coli, the acnA gene (its nucleotide sequence is shown in SEQ ID No: 1) encodes aconitase A, but it may be due to its metabolic distance from the final The l-threonine product is too far away, the intermediate metabolic branches are too many and complicated, and it has not been paid attention to in l-threonine fermentation

[0004] After long-term research and practice, especially with some luck, the inventor accidentally found that the transformation of the regulatory elements of the acnA gene can help Increase the production of l-threonine; however, the prior art either introduces beneficial enzyme genes with increased expression and / or enzymatic activity by increasing copies and / or site-directed mutations, or knocks out unfavorable genes to make them enzymatically active and / or the expression level disappears, but differently, the inventors found that the regulatory elements of the acnA gene cannot be simply improved or knocked out, especially after knocking out acnA gene makes the growth of bacteria difficult and difficult for practical application, so a new method targeting the regulatory element of the acnA gene was developed to increase the production of l-threonine, and the The method does not conflict with the chromosomal modification sites of a large number of high-yield L-threonine-producing bacteria that have been transformed, and the improved effect can be superimposed, so that it can be used in the production of L-threonine by bacterial fermentation in practice