麻豆传媒

ASTRONAUTS may one day be able to use their spacecraft鈥檚 septic tank to keep
in touch with ground control鈥攁s long as they have plenty of sugar.
Scientists in Michigan have developed a biofuel cell that creates a constant,
low-power electricity supply by feeding glucose to common bacteria such as
E. coli.

Biochemists Gregory Zeikus and Doo Hyun Park at Michigan State University in
East Lansing have manipulated the bugs鈥� metabolism to convert them into tiny
powerhouses. They have built a 0.6 volt biofuel cell that can deliver currents
of up to 17 milliamperes.

Bacteria normally break down glucose to generate adenosine
triphosphate鈥� the main energy source for cells. This involves a flow of
electrons, which the researchers have tapped into by adding a chemical called
neutral red. Molecules of neutral red insert themselves into the bacterial
membrane, where they hijack the reaction鈥檚 electron-transport process, and
shuttle electrons onto an electrode.

鈥淚t鈥檚 like an electric plug,鈥� says Zeikus. 鈥淵ou put it in the cell membrane
and put the cells in a cathode to make electricity.鈥� The method isn鈥檛 likely to
be powering your CD player any time soon, but Zeikus says it could be used as a
backup method of maintaining communications in remote areas such as space. There
is a bonus, too. Because some of the bacteria鈥檚 energy is diverted to producing
electricity, they don鈥檛 multiply as fast as usual, leaving less sludge to
dispose of.

Ziekus and Park are not the only researchers exploring the electrical
potential of sugar-fed biofuel cells. Itamar Willner and his colleagues in the
chemistry department of the Hebrew University of Jerusalem in Israel, for
example, are using enzymes rather than bacteria to make batteries that could be
implanted in people鈥檚 bodies. Powered by blood sugar, the batteries could one
day power pacemakers, insulin pumps and prostheses.