In 1990s production of l-malic acid from fumaric acid
using Saccharomyces cerevisiae cells was extensively studied.
Figueiredo and Carvalho have shown that entrapped
Saccharomyces cerevisiae into polyacrylamide gel discs can
produce malic acid form fumaric acid without formation of
by-product. Peleg et al. amplified the yeast S. cerevisiae
for fumarase by cloning the fumarase gene of the same strain
into an expression vector. Afterward Neufeld et al. studied
the kinetics of the bioconversion with this free and immobilized
transformed strain and achieved a very high conversion of
fumaric to l-malic acid without succinic acid formation.