Prof. Zhimin Li

East China University of Science and Technology, Shanghai
 

Abstract:

Succinic acid is a diprotic, dicarboxylic acid with chemical formula C4H6O4. It has wide applications in food, pharmaceutical and chemical industries. Succinic acid is traditionally produced by hydrogenation of maleic acid, oxidation of 1,4-butanediol, and carbonylation of ethylene glycol. Its biological production by microbial fermentation of renewable carbohydrates receives more attention because of concerns about depletion of fossil feedstocks and net emissions of greenhouse gases. Succinic acid is a metabolite of microbial primary metabolism that usually starts with glucose, xylose and glycerol. Very high product yields (e.g. more than one gram of succinic acid per gram of glucose) have been achieved under anaerobic conditions. Now the biological production of succinic acid becomes more and more competitive compared to traditional chemical catalysis.
In our lab, succinic acid also has been formed successfully to a higher titer and productivity via metabolic regulation and metabolic engineering of E. coli. Acetate and Cassava starch as cheap carbon sources were applied into the processes. Two-stage fermentation with acetate as an inducer for the improvement of essential enzymes was studied and developed. Based on the re-directed metabolic pathway, glucose, glycerol and cassava starch could be transformed into succinic acid efficiently. Later, the pathway using acetate as the sole carbon source was also set up and optimized.