When it comes to food there’s no accounting for tastes. Some of us humans prefer steak while others delight in tofu. Among other life forms there is still more variety. There are even microbes that dine on electrons. While all organisms need electrons to provide them with energy, the process of acquiring that energy is usually far more complex than just eating electrons. Our bodies turn the food we eat into energy by reconfiguring its molecules to make its energy available to us. However, scientists have recently discovered microbes that live entirely off energetic electrons from non-organic sources such as the minerals in rocks.
To lure the microbes so that they can be studied, scientists have placed electrodes in the water or sediment where they are suspected to live, hoping the electric current would attract these simple life forms. And it has. A wide variety of microbes have been found, mostly in areas that are low in oxygen but rich in minerals, with habitats ranging from hot deep sea vents to mineral rich rocks deep beneath the Earth’s surface.
Biophysicist Moh El-Naggar of the University of Southern California and his graduate student Yamini Jangir studied microbes in an old gold mine in South Dakota that is now used as a dark matter detector. These microbes belong to a group called lithoautotrophs, or rock eaters, that get their energy from inorganic substances such as manganese, sulfur and iron. Under certain conditions they can live on electricity alone. Annette Rowe, another researcher working with El-Naggar, identified at least thirty new varieties of electricity eating microbes in the iron-rich sediments surrounding California’s Catalina Island. As these bacteria thrive under a range of different electrical conditions they have most likely developed varying strategies for eating electrons.
While research in this field is still in its infancy it seems clear that some microbes can ingest electrons directly. Others have been found to secrete enzymes that grab an electron from an inorganic source and pair it with a proton from water. The microbes then eat the resulting hydrogen.
These discoveries have implications for the search for the origins of life on Earth. One theory posits that life originated on mineral surfaces, and the new research suggests a mechanism for transferring the electrons needed for life from mineral surfaces into cells. The research also has implications for the search for life on other worlds. In just the last few years a wide range of microbes have already been discovered here on Earth that can thrive directly on electrons from non-organic sources in extreme conditions. This suggests that life may be more adaptable than we thought, taking a wide variety of forms both here and perhaps elsewhere in the universe.
While there is no public Stars Club meeting in December, on Friday, January 5th at 7:30pm, the Stars Club and the Springfield Science Museum will host “Stars over Springfield,” an astronomy adventure for the whole family. Amateur astronomer Jack Megas will present “The Brightest Stars of Winter,” a guide to the winter night sky. A fee of $3 for adults and $2 for children under 18 will be charged.
Copyright © Amanda Jermyn