In situ Extractive Fermentation of Lactic Acid by Rhizopus oryzae in an Air-lift Bioreactor

M. Matsumoto and H. Furuta

Abstract
In this paper, the in situ extractive fermentation of lactic acid was developed with Rhizopus oryzae that grew in a medium without costly nutrients such as peptone or yeast extract. Tri-n-octylamine as an extractant and isotridecanol as a diluent were selected in an optimum extraction system from the viewpoint of the tolerance of organic solvents to R. oryzae and extraction capacity. Using this extraction system, batch fermentations were carried out in a stirred tank in the presence of an organic solution. It was found that a higher aeration rate was needed to enhance the production rate of the lactic acid and the extent of its extraction became relatively high due to the absence of extraction inhibitors, peptone and yeast extract. Finally, in situ extractive fermentation was carried out using pelleted R. oryzae in a fed-batch mode in an air-lift reactor. Lactic acid was successfully fermented and extracted from the broth to organic phase for 25 days. (This work is licensed under a Creative Commons Attribution 4.0 International License.)

This work is licensed under a Creative Commons Attribution 4.0 International License

Keywords
in situ extractive fermentation, L-lactic acid, Rhizopus oryzae, trioctylamine, air-lift reactor