oxidative fermentation. It is possible that part of the energy that is
produced and changed into heat through the microbial conversion
of biomass could be harvested as electricity via the application of
MFC technology to oxidative fermentation. However, the coproduction
of a useful material and electricity by the application of
MFC technology to oxidative fermentation has not been reported.
We focused on vinegar production as an initial and model useful
material to be produced by oxidative fermentation in combination
with MFC technology. Acetic acid, the major component of vinegar,
is oxidized from ethanol during fermentation by acetic acid bacteria.
It was reported that the acetic acid bacteria Acetobacter aceti
and Gluconobacter roseus can generate electricity from glucose and
ethanol in an MFC without the addition of electron mediators
(13,14). This characteristic is favorable for ensuring the quality of
the product and enabling a simple subsequent purification process
for the production of useful materials. In this study, acetic acid
fermentation in an MFC system and electricity production during
fermentation by A. aceti were demonstrated. The power generation
characteristics of the cell during repeated batch fermentation were
also investigated.