Three different groups of bacteria such as hydrocarbon-degrading and biofilm-producing microorganisms (Azoarcus, Leptothrix, Acidovorax, Thauera, Pseudomonas, etc.), [Fe.sup.2+]- and [Mn.sup.2+]-oxidizing bacteria (Thiobacillus, Sideroxydans, Gallionella
, Rhodopseudomonas, etc.), and [Fe.sup.3+]- and [Mn.sup.4+]-respiring bacteria (Rhodoferax, Geobacter, Magnetospirillum, Sulfurimonas, etc.) were detected by Benedek et al.
There are many species of these oxidative/reductive bacteria, including Gallionella, Leptothrix and Geobacter metallireducens.
Gallionella is an example of the metal depositors bacteria.
Esteves (1998) comenta a presenca desse elemento nos corpos d'agua e sua interacao com bacterias filamentosas dos generos Gallionella
e Leptothrix que oxidam o [Fe.sup.+2], transformandoo em [Fe.sup.+3] que, por sua vez, podem ser precipitados e o mesmo processo e possivel de ocorrer nas tubulacoes do sistema de irrigacao.
granulata Ehrenberg Frustules rectangular in girdle view joined forming filiform colonies.
For example, proteins in the cell surface of bacteria such as Gallionella
and Crenothrix will oxidize [Fe.sup.2+] and deposit a sheath or ribbon of precipitated Fe[(OH).sub.2].
The rate at which pyrite oxidizes in natural environmental systems is usually accelerated by the action of sulfur and iron oxidizing bacteria such as Thiobacillus sp., Ferrobacillus sp., Gallionella
, Sphaerotilus and others (Langmuir 1997).
When they are either abandoned or closed and managed, their pits and networks of tunnels are inevitably and naturally infested with ancient underground-dwelling microbes, such as Thiobacillus ferrooxidans, Thiobacillus sulfuroxidans, Metallogenium, and Gallionella. These widespread and adaptable microbes were in the coal and metal ores before the miners reached them, and remnant populations remain dormant on the mine walls and in the rocks when the mines are abandoned.
**The Thiobacillus ferrooxidans, Metallogenium, and Gallionella species all react with the metals to remove electrons from them, converting them to positively charged and toxic ionic states.
, a true iron bacteria, is a rod or kidney-shaped bacteria that secretes long, slender, twisted bands or stalks of ferric hydroxide.