2-21: Medium optimization for hexanoic acid production by Megasphaera elsdenii using sucrose

Hexanoic acid was used as a food additives and perfume, and can be converted to hexanol that would be utilized as a transport fuel by chemical catalyst. In this study, representative hexanoic acid producing bacteria, Megasphaera eldenii strains were collected and the substrate specificity and the performance for hexanoic acid production were investigated. Among them, Megasphaera eldenii A11 capable of sucrose utilization as a sole carbon source was selected and produced hexanoic acid up to about 3 g/L. First of all, the production of hexanoic acid was optimized for acetic acid and butyric acid as electron acceptors, respectively, using one-factor-at-time. When acetic acid and butyric acid were added with the strain, the production of hexanoic acid increased according to the increase of concentration of the electron acceptors. Especially, addition of acetic acid increased the cell growth and addition of butyric acid affected the production of hexanoic acid. In order to optimize the production of hexanoic acid and the cell growth, response surface methodology (RSM) was applied. From the Box-Behenken results, the concentration of acetate and butyrate was significant factors and the interaction effect between acetate and butyrate was shown. From the statistical results, the optimized concentration of electron acceptors was predicted for the production of hexanoic acid and the optimized conditions were verified through the practical experiments. As a result, the concentration of hexanoic acid increased up to about 10 g/L within 2 days when the optimized medium was used.