How do bacteria breathe iron?

The idea that the reduction of iron in the environment is a microbial process involving a very special set of bacteria is a relatively new revelation.

To help us understand a little more of this highly complicated and convoluted process, Dr. Patricia J.S. Colberg of the University of Wyoming visited Mines last week to discus the bacterial reduction process. “My talk may be like a Gordian knot, because some think these problems are intractable problems. I don’t think this is intractable.” Colberg went on to explain that the process of bacterial reduction of iron can be understood by examining the surface of the bacteria, where the electron transfer actually takes place.

The process involves only a few proteins, known as cytochromes, that exchange the electrons within iron. Because bacteria are such complicated organisms, Colberg used many different methods to study the reactions. With techniques such as cyclic voltammetry, her assistants were able to uncover the underlying process at work, arriving at the understanding of what these cytochromes were actually doing.

With this new and deeper understanding of the iron reduction process, Colberg believes that advances can be made in many fields of study, such as microbial fuel cells. Because of the electron transfer on the surface of metals by cytochromes, electricity can be generated and fuel cells can now be made more viable. Other real-world applications of this understanding include biogeochemical cycling and remediation of organic contaminants in soils and water.

What’s happening “under the surface,” so to speak, is what makes it all possible. Tiny organisms moving electrons from one place to another cause an electrical potential.