The acetic acid concentration in a batch culture of Acetobacter aceti M23 increased up to 90 g/l by adding ethanol intermittently. Although the bacterial cells ceased growth at about 60 g acetic acid/l, non-viable cells still preserved ethanol oxidation activity. Cell recycling by filtration in a repeated fed-batch culture increased the overall acetic acid production rate 2.84fold compared to that without cell recycling for the purpose of obtaining an acetic acid concentration of 80.8 g/1. Repeated fed-batch cultivation with cell recycle was effective for increasing the production rate of acetic acid and obtaining high amounts close to a lethal concentration (90 g/l).
an ethanol fed-batch culture, in which 500 g/l of ethanol was fed intermittently to the culture to maintain a non-inhibitory ethanol concentration. They succeeded in increasing the acetic acid concentration up to 170 g/1 by this method, while the maximum acetic acid concentration was 120 g/1 in a batch culture without the feeding of ethanol. We adopted the ethanol fed-batch culture according to their method. A repeated ethanol-fed batch culture was carried out with and without cell recycling by membrane filtration, and the results were compared with each other. Moreover, we intended to add quantitative analysis of the production rate of high acetic acid concentrations based on inactivation of cells and inhibition of the production rate.