PI: David Emerson, Bigelow Laboratory for Ocean Sciences
Bacteria are remarkable for their metabolic diversity and ability to utilize seemingly unpalatable food sources. The Fe-oxidizing bacteria (FeOB) are a prime example, since they gain energy for growth by oxidizing ferrous iron to ferric iron (rust). These bacteria are prolific and easily recognized by abundant rust-colored precipitates that form whereever ferrous iron is present in natural waters, or in domestic and industrial water distribution systems. The work funded by this proposal will investigate the systematics, ecology, and physiology of a particular group of freshwater FeOB. The systematics are important because we do not know the true identity of some of the most important FeOB; without knowing who they are it is impossible to reliably identify them. The ecology is important because we know different types of FeOB have very specific habitat requirements. Figuring out those requirements may provide an easy way to determine aspects of water quality that are specific for a given group of FeOB. This could be a good diagnostic tool for assessing water quality. The physiology studies are important because we actually know very little about how, or even why, bacteria oxidize iron. By answering these questions we can learn about an important fundamental biological process. This may allow better control over it, or allow us to harness it for beneficial purposes. To investigate these questions we will employ a host of modern microbiological and chemical techniques that allow us to study cells in their natural environments at the microscale, as well as reproduce those controlled conditions in the laboratory. Ultimately this work will improve our understanding of a long recognized, but poorly understood group of microbes, of significant environmental importance, both as nuisance organisms that cause biofouling and corrosion, and as beneficial organisms that can remove metals and other pollutants from water.