Investigations Into Succinic Acid Fermentation

Succinic acid (SA) is an important chemical intermediate from which fine chemicals ( e.g. detergents), additives (for pharmaceuticals, food (taste), plant growth stimulants) as well as other important intermediates (maleic anhydride, succinimide, 2-pyrrolidinone, dimethyl succinate) can be manufactured. Since SA is involved in the central metabolism of cells (in the tricarboxylic acid (TCA) cycle), it is a key player in the biochemistry of life, which has the potential of biotechnological production. Since SA is formed in the ``middle'' of the TCA cycle it can be formed by both CO2 production and fixation. The significance of the latter is that the amount of the product can be controlled by the availability of CO2, since stoichiometrically one molecule of CO2 is fixed by one molecule of SA. In our studies of compositions of Actinobacillus succinogenes media, the role and effect of pH regulator compounds as well as the effect of an inert atmosphere were investigated in terms of the yield. Furthermore, in fermentation experiments, the application of higher sugar concentrations was also studied. On the basis of different fermentations, a neural network for modelling and describing how factors influence SA production was established.