Iron bacteria

Gelatinous Slime a) Destroy iron bacteria with a solution of hydrochloric acid, then constant chlorination, followed by activated carbon filtration or calcite filter. 

The voluminous deposits associated with iron bacteria, although objectionable in other ways, rarely have much effect on corrosion as they form only over a long period and the alteration in water composition is negligible. 

Metal cycles Iron and manganese oxidation and reduction Iron bacteria and manganese bacteria... 

When deficient in iron, bacteria and fungi produce and excrete to the extracellular medium low molecular weight, specific iron-carrier molecules, called siderophores. These siderophores bind ferric ions, to form soluble complexes. The complexed ferric ions are transported into the cell through high-affinity and energy-dependent receptor proteins located on the outer membrane. In Gram-negative bacteria, such as E. coli, the most studied system, siderophore-iron complexes are transported initially to the periplasm. 

Bacteria are also responsible for destruction of wood, for example in cooling towers,20 by breaking down the cellulose fibers. Certain bacteria derive their metabolic energy from the iron(II)-iron(III) redox cycle. These iron bacteria can proliferate to the extent that they block pipes. In any case, they will discolor water. In addition, objectionable growths of algae can occur in water tanks or circuits, given even minimal supplies of nutrients. Consequently, biocidal agents are widely used in the treatment of industrial, as well as municipal, water supplies. 

Chemoiithotrophic2 bacteria obtain energy from various sources. For example. iron bacteria produce energy by the oxidation of iron(ll) compounds ... 

Act as a secondary biocide, with supporting effectiveness against iron bacteria, fungi, legionella, nitrifiers, etc. 

Biocorrosion (from sulfur bacteria and iron bacteria)... 

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

Several hypotheses of the possible relationship between the deposition of the cherty iron formation and the activity of various primitive organisms have been defined and repeatedly proofs have been offered to support the occurrence of definite biota. In fact, some indication is available for the assumption, that life was abundant at the time and place of deposition of the BIF and that iron formations themselves were deposited as a result of biological processes. It is presumed in this context, that iron-bacteria reacted with the oxygen acceptor Fe2 + in solution and then deposited the trivalent and/or trivalentdivalent iron as precipitated compounds along with other residues resulting from biomass. All these components... 

Fig. 38 a and b. Microstructures resembling iron bacteria contained in the Isua banded iron formation. Fig. b) shows a portion of Fig. a) in higher magnification. Electron micrographs from demineralized rock section (Pflug, 1984b)12+1... 

Weston, Proa. Amer. Soc. Civil Eng., 1908, 34, 1324 9 See Ellis, Iron Bacteria (Methuen, 1920). 

Iron is apt to be troublesome when present in quantities of 1 part per 100,000 and upwards. The metal oxidises, and hydrated oxide (rust) precipitates out on standing this may block the pipes conveying the water. This oxidation is assisted by certain lowly organisms known as iron bacteria.1 Iron salts are not toxic, but have a certain medicinal value and impart a bitter taste to the water. Copper salts are frequently employed to remove algae, 0-3 parts per 100,000 being about the minimum effective concentration of copper sulphate for this purpose. At such dilutions the salt is not prejudicial to the human organism. 

Mumford Proa. Ghent. Soc., 1913, 103, 645) describes an organism through the agency of which a dilute solution of ferrous ammonium sulphate was completely oxidised to feme hydroxide m thirty-six hours at 37° 0, no iron remaining in solution. See also Ellis, Iron Bacteria (Methuen, 1920). 

Aerobic iron bacteria accelerate the formation of tubercles. The sulfate-reducing bacteria flourish in tubercles and can accelerate the corrosion process. 

Mumford has isolated an iron bacillus from Bridgewater Canal Tunnels, Worsley, Lancs. It precipitates iron as a mixture of oxides corresponding to bog ore (Proc. Ghent. Soc., 1913, 29, 79). See also Ellis, hon Bacteria (Methuen, 1920) Raumer, Zeitsch anal. Ghent., 1903, 42, 590 Iron Bacteria, Harder, U.S. Geol. Survey, Professional Paper, No. 113, 1920. 

There are also non-acidophilic iron bacteria, such as the prosthecates Hyphomicrobium,... 

Chukhrov et al. assign a special role to ferrihydrite (2.5 Fe203-4.5 H2O), which is believed to be the typical product of rapid oxidation of Fe + in slightly acid, neutral, and slightly alkaline solutions with the participation of iron bacteria. The oxidation process also is accelerated by the catalytic action of silica. In the course of time ferrihydrite spontaneously converts to hematite, but in solutions with Fe " ions ferrihydrite is transformed into stable goethite in the absence of significant amounts of oxygen. 

The formation of lepidocrocite is possible only in the case of slow oxidation, in particular in solutions with a high carbon dioxide content, in the absence of iron bacteria and significant amounts of free silica. Such conditions are very common in the weathering of siderite. 

Leptothrix ochracea, whereas chemohthoautotrophic iron bacteria reduce CO rather than oxidize ambient organic material by means of Fe(III), yet assuming the same C/N ratio... 

On the top levels of ecosystems and biocoenoses, however, there is no autocatalysis anymore as these systems do not (cannot by definition) reproduce. Rather, they form sources or sinks for elements, acting as a kind of environment for elements autocatalytic to at least some members of the embedded biota. This includes cases where some essential elements becomes deposited (Fe by iron bacteria, Ca by corals, etc., S by sulfate reducers) or transferred to the atmosphere, thus vented in a more (Se, As methyls) or less reactive (N ) form, thus increasing exit orders. With always but a part of the metabolized element mixture being locked up in biomass over longer periods of time, the situation is asymmetric on each trophic level. 

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