Sunday, August 11, 2013
Pavilion (Sheraton San Diego)
Succinic acid (SA), a four-carbon dicarboxylic acid has been reported as one of the top 12 valuable building block chemicals that could be produced via biorefinery process from renewable materials. Succinic acid is a major fermentation product biosynthesized by the bacterial cells of Actinobacillus succinogenes during anaerobic metabolism. In order to enhance volumetric productivity of succinic acid, continuous fermentations were carried out at various dilution rates and production medium compositions. A medium composition optimized statistically (i.e. via the application of OFAT, FFD, SAM and RSM methods) by batch experiments in shake flask fermentations was initially used for the continuous operations with 2L-working volume stirred-tank bioreactor, and then has been gradually modified based on the results of the continuous fermentation process. Steady-state conditions were found to reach around 1.5 day after the start of continuous operations, even though there are a little bit time-differences according to medium composition and dilution rate. Optimum dilution rate showing the highest productivity of succinic acid could be finally determined through intensive chemo-stat experiments. In this paper, important fermentation parameters from the continuous operations such as specific SA production rate (qp), specific growth rate (μ), and specific C-source uptake rate (qs) will be presented, compared with those from the parallel batch fermentations.