Reconstruction of cytosolic fumaric acid biosynthetic pathways in Saccharomyces cerevisiae

Background: Fumaric acid is a commercially important component of foodstuffs, pharmaceuticals and industrial materials, yet the current methods of production are unsustainable and ecologically destructive. Results: In this study, the fumarate biosynthetic pathway involving reductive reactions of the tricarboxylic acid cycle was exogenously introduced in S. cerevisiae by a series of simple genetic modifications. First, the Rhizopus oryzae genes for malate dehydrogenase (RoMDH) and fumarase (RoFUM1) were heterologously expressed. Then, expression of the endogenous pyruvate carboxylase (PYC2) was up-regulated. The resultant yeast strain, FMME-001. up arrow PYC2 + up arrow RoMDH, was capable of producing significantly higher yields of fumarate in the glucose medium (3.18 +/- 0.15 g liter(-1)) than the control strain FMME 001 empty vector. Conclusions: The results presented here provide a novel strategy for fumarate biosynthesis, which represents an important advancement in producing high yields of fumarate in a sustainable and ecologically-friendly manner.