Malic acid is normally produced by a “two-stepfermentation”
process, in which fumaric acid is produced
and then catalyzed to malic acid by fumarate hydratase. In
another synthesis, malic acid is catalyzed directly from
fumaric acid synthesized completely via a chemical method.
Therefore, one-step-fermentation is the optimal method
because it produces malic acid from a normal sugar carbon
source rather than from petrochemical materials. Furthermore,
carbon dioxide is “fixed” in the fermentation process, thereby
mitigating greenhouse gases emissions to some extent.
More attention has been paid to the direct fermentation of
malic acid