One of the most common bacteria in the Earth, Shewanella oneidensis MR-1, uses oxygen as an energy source for respiration. But in the absence of oxygen, Shewanella uses (oxy)hydroxide minerals. These metal particles may also have adsorbed heavy metals on them. As a result, Shewanella influence the mobility and bioavailability of iron and environmental contaminants like lead, cobalt, and arsenic.