Efficient L-Lactic Acid Production by Rhizopus oryzae in Air-Lift Bioreactor using Activated Carbon

Abstract

To produce L-lactic acid efficiently by batch fermentation using Rhizopus oryzae in airlift fermentor, 5 kg/m³ of activated carbon, which was used for post treatment of fermentation broth, was added to fermentation medium. Fermentation broth was decolorized simultaneously with fermentation by activated carbon to obtain clearer fermentation broth. By adding activated carbon from lignite, the cells formed smaller pellets and productivity was improved from 0.824 kg/m³ to 1.10 kg/m³. Further, productivity was improved up to 1.37 kg/m³ by increasing the addition amount of activated carbon to 20 kg/m³ though it was ineffective when adding more. From these results, it was suggested that activated carbon from lignite is effective in enhancing the cell activity for R. oryzae like biological activated carbon.