The production of chemicals from renewable feedstocks using microorganisms has received considerable attention due to the ever increasing possibilities of genetic engineering and the potential to decrease CO2 emissions. Multifunctional molecules containing alcoholic and carboxylic acid groups are especially of interest, because of their application in polymer production which represents a very large market [1]. Four carbon 1,4-diacids (succinic, fumaric, and malic) are amongst the top 12 chemical building blocks manufactured from bio-feed-stocks in a report by the US Department of Energy (USDOE) [2].