9-21: Integration of fermentation and crystallization for fumaric acid production

Fumaric acid (FA) is used in industrial polymerization processes. Currently FA is mainly produced from oil-based feedstock. But as oil resources are becoming scarce, renewable feedstock alternatives processes like fermentation, may be required to supply the future demand of this acid ^[1]. FA fermentation by Rhizopus oryzae is inhibited by the presence of FA and its salts that are formed when neutralizing agent is used to control pH. Salts formation lead to excessive downstream processing requirements and high gypsum production ^[2].  This research aims to produce FA by integration of fermentation and external crystallization. It seeks to avoid the use of neutralizing agents for maintaining pH values at the desired levels and symplifing the number of steps in downstream processesing.

 FA fermentation is carried out by R. oryzae, via reductive and oxidative pathways. R. oryzae can produce 0.9 g FA/(l·h) in stirred tank fermentation at pH 5 ^[3]. However, for mantaining this pH value neutralizing agent has to be added. In order to avoid neutralizing agent addition, the concept of fermentation at low pH plus product removal by external crystallization of uncharged FA will be developed ^[4].

 References:
[1] Roa Engel et al. 2008. Appl. Microbiol. Biotechnol. 78 379 389
[2] Zhou et al. 2002. Bioproc. Biosyst. Eng. 25  179 – 181.
[3] Cao et al. 1996. Appl. Environ. Microbiol. 62  2926-2931.
[4] Buque et al. 2006. Appl. Environ. Microbiol. 71  1-12.