For 11 years, Jill Banfield has collected and studied the microbes that slime the floors of mines and convert iron to acid, a common source of stream pollution around the world. Imagine her surprise, then, when research scientist Brett Baker discovered three new microbes living amidst the bacteria she thought she knew well—smaller than any other known cellular life form.
“We were essentially looking for new stuff,” says Baker, “and we found it.”
Banfield, a professor of environmental science, policy, and management and of earth and planetary science, has been trying to understand how such extremophiles—microbes that live in extreme environments—live together and generate the acid drainage that makes such mines toxic hazards. The collaborators have been using advanced genetic sequencing techniques to identify newly discovered microbes—both bacteria and a type of organism known as Archaea. When Baker turned up the three Archaea from a totally unknown group, he was able to fish the microbes out of the slime soup and measure their diameter at about 200 nanometers. As the New York Times reported, “four million of the newly discovered microbes could fit in the period at the end of this sentence.”
All of which means that, as the researchers put it when they published their discovery, “It may be necessary to reconsider existing paradigms for the minimum requirements for life.”