Yeast cells having reductive TCA pathway from pyruvate to succinate and overexpressing an exogenous NAD(P+) transhydrogenase enzyme

A process for producing succinate, comprising culturing a recombinant yeast cell under fermentation conditions in a fermentation broth that includes a sugar that is fermentable by the cell, wherein the recombinant yeast cell has an active reductive tricarboxylic acid (TCA) pathway from pyruvate or phosphoenolpyruvate to succinate,

• wherein the recombinant yeast cell is modified from a parent yeast cell by having integrated into its genome an exogenous gene encoding a soluble nicotinamide adenine dinucleotide phosphate (NAD(P)+) transhydrogenase enzyme, wherein the soluble NAD(P)+ transhydrogenase enzyme is expressed in the cytosol of the recombinant yeast cell,
• wherein the recombinant yeast cell is further modified from the parent yeast cell by having integrated into its genome an exogenous gene selected from the group consisting of:
• (i) an exogenous pyruvate carboxylase gene that encodes an enzyme which catalyzes the conversion of pyruvate to oxaloacetate,
• (ii) an exogenous malate dehydrogenase gene which encodes an enzyme that catalyzes the conversion of oxaloacetate to malate,
• (iii) an exogenous fumarase gene that encodes an enzyme which catalyzes the conversion of malate to fumarate,
• (iv) an exogenous fumarate reductase gene which encodes an enzyme which catalyzes the conversion of fumarate to succinate, and
• (v) combinations thereof,
• wherein the recombinant yeast cell produces more succinate through the active reductive TCA pathway as compared to the parent cell.