Advances in biotechnological production of butyric acid

The review is focused on several aspects of butyric acid production: butyric acid-producing bacterial strains, the characteristics of the genus Clostridium (the bacterium most used for butyrate production), and alternative methods of obtaining butyric acid by alcohol biotransformation. Further, the main metabolic pathways of butyrate production, and possibilities for their control are outlined. Batch, fed-batch or continuous fermentation combined with cell recycle or Immobilization are applicable for anaerobic fermentations using Clostridium as the production strain, The best process comprises a combination of high cell concentration and slowly growing biomass, in addition to high production selectivity and low inhibitory effects of the end-product, Inhibitory effects may be avoided by on-line removal of the end-product, Extraction alone or extraction combined with simultaneous stripping of the organic phase (liquid membrane) into the second aqueous phase (pertraction) seem to be the most suitable methods for online butyrate removal, The biocompatibility and the distribution coefficient of the organic phase under fermentation conditions should be considered before designing a fermentation apparatus.