Natures wonders: some bacteria live on electrons (Introduction)

by David Turell , Thursday, June 16, 2016, 02:01 (3081 days ago) @ David Turell

No need for oxygen at all:-http://www.bbc.com/earth/story/20160613-there-are-microbes-that-eat-and-poo-nothing-but-electricity-"Some microbes have developed the ultimate stripped-down diet. They do not bother with food or oxygen. All they need to survive is pure electrical energy.-"They often live in muddy seabeds or along the banks of rivers. Finding them is easy: biologists can coax them out of hiding by sticking an electrode into the sediment. The bacteria nearest to the electrode will even grow biological equivalents of electrical wires out of their bodies, so that other microbes further away can hook up to the electricity source. It is effectively a living power grid.-***-"The microbes, called Geobacter metallireducens, were getting their electrons from organic compounds, and passing them onto iron oxides. In other words they were eating waste - including ethanol - and effectively "breathing" iron instead of oxygen.-***-" Instead, the bacteria pass their electrons to metal oxides that lie outside the cell.-"They do this through special hair-like wires that protrude from the cell's surface. These tiny wires act in much in the same way that copper wire does when it conducts electricity. They have been dubbed "microbial nanowires".-***-"Geobacter bacteria are able to survive on energy sources entirely unavailable to most lifeforms.-"They are even able to effectively "eat" pollution. They will convert the organic compounds in oil spills into carbon dioxide, or turn soluble radioactive metals like plutonium and uranium into insoluble forms that are less likely to contaminate groundwater - and they will generate electricity in the process.-***-"Different species of bacteria and archaea - ancient single-celled microbes similar to bacteria in many ways - team up to degrade the methane before it can get the surface.
It seems that the bacteria use these nanowires to hook up with the archaea.-"The archaea feed on electrons from methane, oxidising the gas to generate carbonate. They then pass the electrons on to their partner bacteria along the nanowires, which act like power cables. Finally the bacteria deposit the electrons onto sulphate, producing energy that the cell can use in the process.-***-"While most organisms get their electron fix from carbohydrates, some bacteria can harvest electrons in their purest form. They can effectively "eat" electrons from minerals and rocks. In a way, they are getting their electrical energy straight from the socket.-"Annette Rowe, a graduate student of Nealson, has found six new bacterial species on the ocean floor that can live off electricity alone. All are very different to one another, and none of them is anything like Shewanella or Geobacter.-***-"Many more electron-loving bacteria have now been found. In fact all you have to do is stick an electrode in the ground and pass electrons down it, and soon the electrode will be coated with feeding bacteria. Experiments show that these bacteria essentially eat or excrete electricity.-***-"Lovley and his lab have also discovered other communities of bacteria that are able to pass electrons directly to each other.-""In the lab, Lovley showed that two species of Geobacter - G. metallireducens and G. sulfurreducens - survive by forming a conductive network of nanowires, through which electrons can be shuttled. G. metallireducens takes electrons from ethanol and then passed them directly to G. sulfurreducens using this electrical grid.-In a more extreme version of this process, some bacteria can link up to form long "cables".-
***-"If life exists on other worlds, such as Mars or Jupiter's moon Europa, it will probably be in similarly sparse environments. Astrobiologists searching for evidence of extraterrestrial life might be particularly interested in electricity-eating and electricity-excreting microbes.-"Whether or not such alien life is ever found, electricity-eating and -excreting bacteria here on Earth are still a significant discovery. All you need to do is provide them with an electrode onto which they can "breathe" electrons, and they have the potential to steal electrons from toxic waste, oil spills and nuclear waste, cleaning up our waste and generating electricity in the process.-"Not bad for simple single-celled organisms."-Comment: Perhaps this is how life started? Note how Archaea work with the electron eaters Very long article. Worth reviewing all of it since there is much more info about different life styles.