Genetically engineered bacterium for producing L-threonine as well as construction method and application of genetically engineered bacterium

Abstract

The invention discloses a genetically engineered bacterium for producing L-threonine as well as a construction method and application of the genetically engineered bacterium. The biotin synthesis of the L-threonine producing strain is enhanced, especially the pyc gene of the strain is enhanced, and the adopted specific means is to enhance the bioABFCD gene (including promoter enhancement, RBS sequence enhancement and multi-copy), release the transcription repression of the brA gene, and release the transcription repression of the brA while enhancing the bioABFCD. According to the constructed genetically engineered bacterium for producing the L-threonine, through fermentation culture, the yield of the L-threonine can reach 20.2 g / L, and the conversion rate of saccharic acid can reach 23.8%.

Description

technical field

[0001] The invention relates to the field of biotechnology, in particular to a genetic engineering bacterium producing L-threonine and its construction method and application. Background technique

[0002] L-threonine is one of the 8 kinds of amino acids necessary for the growth of humans and animals. It is widely used in feed, food additives and preparation of pharmaceutical auxiliary materials. At present, L-threonine is mainly produced by microbial fermentation, and various bacteria can be used for L-threonine production, such as wild-type induced mutants of Escherichia coli, Corynebacterium, Serratia, etc. as production strains. Specific examples include mutants resistant to amino acid analogs or various auxotrophs such as methionine, lysine, and isoleucine (Japanese Patent Application Laid-Open No. 224684 / 83; Korean Patent Application Laid-Open No. 8022 / 87). However, traditional mutation breeding is difficult to obtain high-yield strains due to the slow...

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