Aspergillus niger strain efficiently producing malic acid, construction method and application

Abstract

The invention relates to an Aspergillus niger gene engineering strain efficiently producing malic acid. The Aspergillus niger gene engineering strain is an Aspergillus niger gene engineering strain which knocks out a citric acid transporter gene cexA, and overexpresses a glucose transporter gene mstC, a hexokinase gene hxkA, a phosphofructokinase gene pfkA, and a pyruvate kinase gene pkiA which are derived from Aspergillus niger. The efficiency for producing malic acid of the Aspergillus niger gene engineering strain is significantly improved, the output on the eighth day through fed-batch fermentation in a fermentation tank reaches 195.72-210 g/L, a conversion rate of malic acid to glucose reaches 1.59-1.64 mol/mol, and a fermentation cycle is shorter by one day compared with a starting strain, namely the fermentation cycle is shortened from original 9 days to 8 days. An excellent strain for the preparation of malic acid by microbial fermentation methods is provided.

Description

technical field [0001] The invention belongs to the technical field of microorganisms, in particular to an Aspergillus niger strain for efficiently producing malic acid, a construction method and application thereof. Background technique [0002] As an important cell factory, Aspergillus niger has been used in the fermentative production of organic acids for more than 100 years. It is not only a GRAS (generally regarded safe) strain, but also able to utilize cheap carbon sources. L-malic acid, also known as 2-hydroxysuccinic acid, is mainly used in food, medicine and other industries. In the food industry, L-malic acid is mainly used as a food sour agent. Compared with citric acid, it has the characteristics of soft taste, high acidity, and long residence time. It does not damage the oral cavity and teeth, and does not accumulate fat. The safe food sour agent recognized by the international food industry is one of the organic acids with the largest amount and good developme...

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Problems solved by technology

[0003] At present, the production of malic acid by fermentation of Aspergillus niger has problems such as low production efficiency, long fermentation production cycle and high accumulation of by-product citric acid, resulting in high production cost and subsequent complicated malic acid separation and purification process. Therefore, it is ne...

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