In one experiment, a 160 mM suspension of orange lepidocrocite γ- in a solution containing formate (), incubated for 3 days with a culture of S. putrefaciens, turned dark green due to the conversion of the hydroxide to GR(), in the form of hexagonal platelets with diameter ~7 µm. In this process, the formate was oxidized to bicarbonate which provided the carbonate anions for the formation of the green rust. The live bacteria were shown to be necessary for the formation of the green rust.
