Shewanella oneidensis growing on a metal (iron oxide) from https://asknature.org/strategy/bacteria-reduce-iron-oxide/#.WUA49GjyvIU
From the depths of Lake Oneida in New York comes a very interesting type of bacterium, Shewanella oneidensis. Shewanella is special organism in that it can survive with, or without oxygen. As humans, our metabolism requires that we take in food and oxygen to produce carbon dioxide and water. Shewanella also has this ability, but when oxygen is not present in the environment, they are able to use minerals and metals in the environment for what we as humans need oxygen for. For example, when we break down glucose, we make energy. The byproducts of that reaction eventually end up needing to go somewhere, and the cells in our bodies use oxygen as that place, making water. Obviously, humans cannot survive without oxygen, but Shewanella can! When they break down a food source to make energy, they also need to get rid of the byproducts…but wait, they don’t have oxygen. The cool thing about Shewanella is that they have proteins on their surface that allow them to pass those byproducts to things in the environment by contact. When the byproducts are passed to the environment, it produces an electrical current. So, our goal is to harvest the electricity produced, but in E. coli. The proteins that allow Shewanella to do this are encoded for in the genes that we are going to put into E. coli! Why would we use E. coli and not just Shewanella? One reason is that what we are doing has never been done before! It’s pretty awesome to think that we are taking genes from one organism and putting them into another to get a result that has never been observed, EVER!!! Also, scientists use E. coli for these types of tests because it’s easy to use. So many studies have been done on E. coli that we know so much about it, and in a lab setting, we can pretty much try and make it do whatever we would like.