http://synbioproject.tech/cpi/applications/fumaric-acid/
Fumaric acid is commonly used as a preservative in food and beverages, in the production of paints and coatings, as well as in the production of paper. It is the chemical equivalent of maleic anhydride (MAN) and water, and therefore can be used as a replacement for MAN. Source
Using patented, genetically modified microorganisms as biocatalysts, Myriant converts renewable cellulosic feedstocks into basic industrial chemicals and compounds.