Iron Bacteria

bacteria that are able to oxidize ferrous iron compounds and to use the energy thus liberated to assimilate carbon from carbon dioxide or carbonates. The equation for the oxidation is

4Fe(HCO₃)₂ + 6H₂O + O₂ = 4Fe(OH)₃ +4H₂CO₃ + 4CO₂

In this reaction a small amount of energy is liberated; there-fore, iron bacteria oxidize a large amount of ferrous iron.

The iron bacterium whose physiology and biochemistry has been studied the most thoroughly is the nonsporiferous, mobile bacillus Thiobacillus ferrooxidans, which also oxidizes sulfur. The iron bacteria also include some thread bacteria of the species Leptothrix, with thick rust-colored capsules (sheaths) containing hydrated iron oxide, and Gallionella, which consists of clusters of extremely fine threads (0.01 micron) twisted into spirals, forming pedicles on whose surface hydrated iron oxide is deposited. Iron bacteria live in fresh and salty bodies of water and play a large role in the iron cycle in nature. On the bottoms of bodies of water, iron bacteria form dark brown disk-shaped concretions consisting of iron and manganese.