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 ↑PYC2 + ↑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.