The present invention provides a genetically engineered bacterium producing malic acid and its method of malic acid production, including increasing the expression or activity of dicarboxylic acid transporter protein in the recipient bacterium, decreasing the expression or activity of methyltransferase laeA in the recipient bacterium, and obtaining the engineered bacterium producing malic acid. The present invention effectively increases the yield of malic acid. Furthermore, by introducing acid-tolerant engineered bacteria, the use of neutralizers is effectively avoided.
The present invention has discovered a new approach to effectively increase the yield of malic acid, specifically by reducing the expression or activity of methyltransferase laeA in the recipient bacterium, and increasing the expression or activity of dicarboxylic acid transporter protein in the recipient bacterium. Furthermore, the present invention provides a method for producing acid-tolerant malic acid engineered bacteria, including reducing the expression or activity of methyltransferase laeA in the recipient bacterium, and increasing the expression or activity of dicarboxylic acid transporter protein in the recipient bacterium, obtaining malic acid engineered bacterial strains with acid-tolerant characteristics, thereby avoiding the use of neutralizers.
