Crenothrix

Other iron oxidizers include Sphaerotilus, Crenothrix, and Lep-tothrix species. Each bacterium is filamentous. 

The carbon dioxide produced can contribute to the corrosion of metal. The deposits of ferric hydroxide that precipitate on the metal surface may produce oxygen concentration cells, causing corrosion under the deposits. Gallionalla and Crenothrix are two examples of iron-oxidizing bacteria. 

Crenothrix sp. Iron oxidizer with filamentous sheath. The base of the sheath is usually thickly encrusted with iron and attached to a solid surface. 

Iron bacteria Filamentous, aerobic bacteria Examples are Crenothrix polyspora and Gallionella ferrugine. Also Leptothrix ochracea, Sidero-capsa and Ferrobacillus sp., and ThiobaciUus ferroxidans. 

Fresh-watex forms with easily discernible sheath— Crenothrix. 

FIGURE 4.22 Filamentous lOB Crenothrix present in bore water. The brown matter is ferric hydroxide from oxidation of iron in steel. (From Boulton L., Microbiologically Influenced Corrosion—Case Studies in Australia, Australasian Corrosion Association, Australia, 2007. With permission.)... 

Some examples of lOB are Gallionella, Sphaerotilus, Siderocapsa, and Crenothrix Recently, two new lOB isolates, namely, Gordonia sp. MZ-89 and Enterobacter sp. MOllOl, have been shown to have measurable effects on carbon steel corrosion. Figure 4.24 shows some of the findings on these new lOB isolates. 

For this reason, iron concentrations below 0.1 mg/1 are suitable for central drinking water supply plants. 0.2 to 0.3 mg/1 Fe can be tolerated. However, concentrations of this order may be sufficient to propagate the development of iron bacteria (Leptothrix, Gallionella, Crenothrix). These promote and accelerate the conversion of divalent to trivalent iron which, as a hydroxide precipitate together with the gelatinous bacteria colonies (and in conjunction with manganese bacteria), may lead to the accumulation of mud and sedimentation. 

Fig. 134 - 137. Iron bacteria 1) = Crenothrix polyspora, "spring filament" ...

Iron Galionella Crenothrix Leptothrix 10-30 5.5-8 Piping, water lines Forms slime deposits... 

Crenothrix polyspora A genus of filamentous bacteria which utilize iron in their metabolism and cause staining, plugging, and taste and odor problems in water systems. (See iron bacteria.)... 

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