THE PRODUCTION OF ACETIC-ACID FROM CARBON-DIOXIDE AND HYDROGEN BY AN ANAEROBIC BACTERIUM

For the advantageous utilization of carbon dioxide (CO2), we developed a bioreactor that produces acetic acid from CO2 using hydrogen (H2) as the energy source. BR-446 (genus Acetobacterium), which has the highest rate of acetic acid production of the many acetogenic anaerobes isolated in our laboratory, was chosen for the study. Its specific production rate was 3.6 g g-1 h-1. The production rate was affected by the dissolved hydrogen concentration (DH2) and was found to have a higher value at a low DH2 level. As the bioreactor, the membrane-filtration type was superior to the immobilized cell type. A constant, continuous acetic acid production for over 1000 h was established using the membrane-filtration type reactor. To further improve productivity, pressurization of the reactor system proved to be effective. Finally, a productivity of 149 g l-1 d-1 was established at high cell density and this value is promising for the future industrial application of this system. © 1990.