Method AMD strains for reducing byproduct fumaric acid in fermentation process of L-malic acid and use thereof

A method of constructing an Aspergillus niger engineered strain for reducing byproduct fumaric acid in a fermentation process of L-malic acid, wherein a fumarate hydratase gene fum is knocked out from the Aspergillus niger engineered strain;

• the amino acid sequence encoded by the fumarate hydratase gene fum is SEQ NO:2;
• the gene sequence of the fumarate hydratase gene fum is NCBI-locus_tagANI_1_952104;
• the method comprises:
• (1) respectively amplifying upstream and downstream sequence fragments of a gene fum through PCR reaction with a wild type Aspergillus niger ATCC1015 genome as a template, and recovering PCR products to respectively obtain target fragments;
• and cloning the upstream and downstream sequence fragments of the gene fum onto a vector pLH594, so as to construct a fumarate hydratase gene fum knockout vector pLH804;
• wherein the upstream sequence of the gene fum is SEQ NO:3, and the downstream sequence of the gene fum is SEQ NO:
• 4;
• (2) transferring the vector pLH804 into an Aspergillus niger malic acid high-yield strain S1149, and conducting transformant screening and hygromycin resistance gene recombination to obtain an Aspergillus niger fumarate hydratase gene fum knockout strain M1,
• wherein the Aspergillus niger engineered strain is obtained by knocking out only the gene sequence of the fumarate hydratase gene fum.