Chemotrophs are organisms that obtain energyby the oxidation of electron donorsin their environments. The chemotroph designation is in contrast to phototrophs, which use solar energy. Iron oxidising bacteria are chemotrophic bacteria that derive the energy they need to live and multiply by oxidising dissolved ferrousiron. They are known to grow and proliferate in waters containing iron concentrations as low as 0.1 mg/L. Iron oxidising bacteria use oxygen to convert the soluble ferrous iron back into an insoluble reddish precipitate of ferric iron, which can be seen by the naked eye.
The dramatic effects of iron bacteria are seen in surface waters as brown slimy masses on stream bottoms and lakeshores or as an oily sheen upon the water. More serious problems occur when bacteria build up in well systems. Iron bacteria in wells do not cause health problems, but they can reduce well yields by clogging screens and pipes.
Fotos: Rasmus Sigvaldi