Researchers Are on the Way to Understand Bacteria That Breathe Rock

It is not a metaphor. Shewanella oneidensis is the name of this strange form of life. It is a bacterium notable for its ability to reduce metal ions and live in environments with or without oxygen. It got its name from the place it was first isolated from, Lake Oneida, NY in 1988.

About Shewanella oneidensis

It is a facultative bacterium, capable of surviving and proliferating in both aerobic and anaerobic conditions. Its behavior in an anaerobic environment contaminated by heavy metals (such as iron, lead, and uranium) leads to the special interest researchers had in it. Cellular respiration for these bacteria is not restricted to heavy metals. Shewanella oneidensis also target sulfates, nitrates, and chromates when grown anaerobically.

Its ability to reduce and absorb heavy metals makes it a candidate for use in wastewater treatment. The bacteria can change the oxidation state of metals. These microbial processes allow exploration of novel applications, for example, the biosynthesis of metal nanomaterials.

But scientists couldn’t understand how the bacteria can breathe rock. The latest study trying to find an answer, claims that it got one: membrane extensions featuring electron-carrying proteins called cytochromes. “If you don’t give it an electron acceptor, it dies. It dies pretty rapidly,” explained USC microbiologist Kenneth Nealson.

The study

The researchers found that as electrons are transported their direction of electron spin seems to be influenced by the chirality of the cytochrome molecules.

Chirality is the geometric property of a molecule or ion to not be superposed on its mirror image by any combination of rotations and translations. A chiral molecule or ion exists in two stereoisomers that are mirror images of each other, called enantiomers: the right-handed and the left-handed.

“This study is the first to confirm that the electrically conductive proteins in these cells are selecting the spin of electrons,” says Moh El-Naggar USC microbiologist. Spintronics technologies are to take advantage of the discovery. More powerful computers can be developed using the newfound feature of Shewanella oneidensis.

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