We?ve told you all about power of slug slime ? but now we’re going to go one weirder. The word is sludge: septic tank sludge, to be precise, and a pair of Michigan scientists who?ve developed a biofuel cell that creates a constant, low-power electricity supply by feeding glucose to common bacteria such as E.coli. It looks like astronauts could soon be able to use their spaceship?s septic tank to keep in touch with ground control. Gregory Zeikus and Doo Hyun Park, biochemists at Michigan State University, have manipulated the metabolism of the E.coli bug and succeeded in converting them into tiny powerhouses. They?ve built a 0.6 volt biofuel cell that can deliver currents of up to 17 milliamperes. This has been achieved by tapping the flow of electrons used in breaking down glucose to ADP (Adenosine Triphosphate, the main energy source of cells). In essense the electrons are hijacked from their usual purpose and shuttled onto an electrode. ?It?s like an electric plug,? says Zeikus. ?You put it in the cell membrane and put the cells in a cathode to make electricity.? Other researchers looking at the area, which could be used to provide cheap backup power in areas such as space exploration, are a team at the Hebrew University of Jerusalem in Israel. They?re using enzymes rather than bacteria to make batteries that could be placed in human bodies ? to power pacemakers, insulin pumps and the like.