Conversion of glucose-xylose mixtures to pyruvate using a consortium of metabolically engineered .

Two strains of were engineered to accumulate pyruvic acid from two sugars found in lignocellulosic hydrolysates by knockouts in the , , , and genes. Additionally, since glucose and xylose are typically consumed sequentially due to carbon catabolite repression in , one strain (MEC590) was engineered to grow only on glucose while a second strain (MEC589) grew only on xylose. On a single substrate, each strain generated pyruvate at a yield of about 0.60 g/g in both continuous culture and batch culture. In a glucose-xylose mixture under continuous culture, a consortium of both strains maintained a pyruvate yield greater than 0.60 g/g when three different concentrations of glucose and xylose were sequentially fed into the system. In a fed-batch process, both sugars in a glucose-xylose mixture were consumed simultaneously to accumulate 39 g/L pyruvate in less than 24 h at a yield of 0.59 g/g.