초록
<P><SMALL>L</SMALL>-Methionine is the only sulfur-containing amino acid among the essential amino acids, and it is mainly produced by the chemical method in industry so far. The fermentation production of <SMALL>L</SMALL>-methionine by genetically engineered strains is an attractive alternative. Due to the complex metabolic mechanism and multilevel regulation of the synthesis pathway in the organism, the fermentation production of <SMALL>L</SMALL>-methionine by genetically engineered strains was still not satisfied. In this study, the biosynthesis pathway of <SMALL>L</SMALL>-methionine was regulated based on the previous studies. As the competitive pathway and an essential amino acid for cell growth, the biosynthesis pathway of <SMALL>L</SMALL>-lysine was first repaired by complementation of the <I>lysA</I> gene <I>in situ</I> on the genome and then replaced the <I>in situ</I> promoter with the dynamically regulated promoter P<SUB><I>fliA</I></SUB> to construct a nonauxotroph strain. In addition, the central metabolic pathway and <SMALL>L</SMALL>-cysteine catabolism pathway were further modified to promote the cell growth and enhance the <SMALL>L</SMALL>-methionine production. Finally, the <SMALL>L</SMALL>-methionine fermentation yield in a 5 L bioreactor reached 17.74 g/L without adding exogenous amino acids. These strategies can effectively balance the contradiction between cell growth and <SMALL>L</SMALL>-methionine production and alleviate the complexity of fermentation operation and the cost with auxotroph strains, which provide a reference for the industrial production of <SMALL>L</SMALL>-methionine by microbial fermentation.</P><BR>[FIG OMISSION]</BR>