Microbial fuel cells (MFCs) provide new opportunities
for the sustainable production of energy from biodegradable,
reduced compounds. MFCs function on different
carbohydrates but also on complex substrates
present in wastewaters. As yet there is limited information
available about the energy metabolism and
nature of the bacteria using the anode as electron
acceptor; few electron transfer mechanisms have been
established unequivocally. To optimize and develop
energy production by MFCs fully this knowledge is
essential. Depending on the operational parameters of
the MFC, different metabolic pathways are used by the
bacteria. This determines the selection and performance
of specific organisms. Here we discuss how bacteria use
an anode as an electron acceptor and to what extent
they generate electrical output. The MFC technology is
evaluated relative to current alternatives for energy
generation.