We focused on vinegar production, i.e., acetic acid fermentation, as an initial
and model useful material that can be produced by oxidative fermentation in combination with MFC technology. The
coproduction of acetic acid and electricity by applying MFC technology was successfully demonstrated by the simul-
taneous progress of acetic acid fermentation and electricity generation through a series of repeated batch fermenta-
tions. Although the production rate of acetic acid was very small, it increased with the number of repeated batch
fermentations that were conducted. We obtained nearly identical (73.1%) or larger (89.9%) acetic acid yields than that
typically achieved by aerated fermentation (75.8%). The open-cycle voltages measured before and after fermentation
increased with the total fermentation time and reached a maximum value of 0.521 V prior to the third batch
fermentation. The maximum current and power densities measured in this study (19.1 mA/cm2 and 2.47 mW/cm2
,
respectively) were obtained after the second batch fermentation.