Engineering strain for efficiently expressing MccJ25 and fermentation process of engineering strain

Abstract

The invention provides an engineering strain for efficiently expressing MccJ25. The engineering strain is used for solving the problem of low expression level of Microcin J25 in the prior art. The engineering strain is constructed by the following method: genetic operation is separately carried out on mcjABCD to become a direction, a promoter T7 is shared in Escherichia coli and is cloned on a vector pBR322, high-efficiency expression in the Escherichia coli is realized, and the expression level is 2.4 g/L. According to the scheme, new expression vectors are constructed, an Escherichia coli expression vector and a lactobacillus plantarum expression vector are separately constructed to efficiently express the MccJ25, meanwhile, a directed evolution technology is adopted, molecular evolution is performed on an MccJ25 gene cluster, and efficient expression of the MccJ25 is realized. Extracellular expression is carried out on the Escherichia coli, intracellular expression is carried out on lactobacillus plantarum, the expression levels reach 4.1g/L and 2.3g/L separately, an industrialization level is achieved, and a foundation is laid for further application of biological veterinary drugs and feed additives.

Description

technical field [0001] The scheme belongs to the field of genetic engineering technology and fermentation optimization technology, and specifically relates to an engineering strain highly expressing MccJ25 and its fermentation process. Background technique [0002] Lasso peptide MccJ25 is a bacteriocin antimicrobial peptide first discovered in Escherichia coli AY25, isolated from human feces (Blond et al., 1999). The synthesis of lasso peptide MccJ25 involves four genes, namely mcjA, mcjB, mcjC and mcjD (Solbiati et al., 1996). [0003] The mcjA gene is 174bp long and is the precursor of MccJ25. During the process of processing and maturation, the N-terminal 37aa is excised to form MccJ25. In the lasso peptide Mcc J25, the 8 amino acids at the N-terminal form a circular ring structure, and the 9-21 amino acids form a β-hairpin structure that runs through the ring. Through biochemical and nuclear magnetic resonance studies, it was found that the 8 amino acids at the N-termi...

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Problems solved by technology

[0009] This solution provides an engineering strain that highly expresses Mc

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