Name: microbes driving iron and manganese cycles
Uploaded: 2026-03-12T13:57:36.000Z
Duration: 1 min 24 s
Channel: JoVE

Mikroby napędzają cykl żelaza i manganu, przesuwając te pierwiastki między ich utlenioną a zredukowaną formą.W neutralnych, bogatych w tlen siedliskach, żelazo żelazne dominuje w formie nierozpuszczalnej, wytrąconej.Niektóre bakterie wydzielają małe cząsteczki zwane sideroforami, które wiążą się z żelazem żelaznym i je rozpuszczają.Komórki następnie pobierają to rozpuszczalne żelazo i redukują je do formy żelaznej do zastosowań metabolicznych.Na styku oksyczno-anoksyczne, gdzie poziom tlenu jest niski, bakterie magnetotaktyczne, takie jak Magnetospirillum , wykorzystują żelazo do tworzenia kryształów magnetytu, ustawiając się z polem magnetycznym Ziemi, aby dotrzeć do warstw beztlenowych.W tej samej strefie bakterie nitkowate, takie jak Leptothrix, utleniają żelazo żelazne, tworząc powłoki pokryte tlenkami żelaza.Utleniają także mangan(II) do nierozpuszczalnego dwutlenku manganu, który może opadać do głębszych warstw beztlenowych, gdzie bakterie redukujące metale, takie jak Geobacter , przekształcają go z powrotem w mangan (II).W strefach beztlenowych bakterie takie jak Shewanella przeprowadzają redukcję żelaza dysymilacyjnego, gdzie żelazo żelazne jest końcowym akceptorem elektronów.

microbes and other elemental cycles

Microbes and Other Elemental Cycles

Aktywno&#x15B;&#x107; mikroorganizm&#xF3;w odgrywa kluczow&#x105; rol&#x119; w biogeochemicznym obiegu &#x17C;elaza i manganu, zw&#x142;aszcza w gradientach redoks charakterystycznych dla uwarstwionych &#x15B;rodowisk wodnych. Cykle te s&#x105; nap&#x119;dzane przez mikrobiologiczne przemiany mi&#x119;dzy utlenionymi i zredukowanymi formami tych metali, co pozwala organizmom wykorzystywa&#x107; je do cel&#xF3;w metabolicznych i strukturalnych.
Obieg &#x17C;elaza wzd&#x142;u&#x17C; gradient&#xF3;w redoks
W oboj&#x119;tnych, bogatych w tlen wodach powierzchniowych &#x17C;elazo wyst&#x119;puje g&#x142;&#xF3;wnie w utlenionej, nierozpuszczalnej formie &#x17C;elazowej [Fe(III)]. Aby uzyska&#x107; dost&#x119;p do tego niezb&#x119;dnego sk&#x142;adnika od&#x17C;ywczego, niekt&#xF3;re bakterie syntetyzuj&#x105; i wydzielaj&#x105; syderofory &#x2014; zwi&#x105;zki organiczne o ma&#x142;ej masie cz&#x105;steczkowej i wysokim powinowactwie do &#x17C;elaza(III). Cz&#x105;steczki te wi&#x105;&#x17C;&#x105; &#x17C;elazo(III), czyni&#x105;c je rozpuszczalnym i dost&#x119;pnym do pobrania. Po internalizacji &#x17C;elazo(III) jest enzymatycznie redukowane do formy &#x17C;elaza(II), kt&#xF3;ra jest bardziej biodost&#x119;pna i wspiera r&#xF3;&#x17C;ne funkcje kom&#xF3;rkowe.
Na granicy tlenowo-beztlenowej, gdzie warunki redoks ulegaj&#x105; wahaniom, bakterie takie jak Leptothrix utleniaj&#x105; rozpuszczalne &#x17C;elazo(II) do &#x17C;elaza(III), tworz&#x105;c zewn&#x105;trzkom&#xF3;rkowe os&#x142;onki tlenkowe. Os&#x142;onki te pe&#x142;ni&#x105; podw&#xF3;jn&#x105; funkcj&#x119;: zapobiegaj&#x105; inkrustacji kom&#xF3;rek i mog&#x105; zapewnia&#x107; wsparcie strukturalne. Bakterie magnetotaktyczne, r&#xF3;wnie&#x17C; wyst&#x119;puj&#x105;ce w tej strefie, internalizuj&#x105; &#x17C;elazo w celu biomineralizacji kryszta&#x142;&#xF3;w magnetytu (Fe&#x2083;O&#x2084;). Kryszta&#x142;y te dzia&#x142;aj&#x105; jak wewn&#x105;trzkom&#xF3;rkowe kompasy, ustawiaj&#x105;c si&#x119; zgodnie z polem magnetycznym Ziemi i kieruj&#x105;c kom&#xF3;rki w stron&#x119; &#x15B;rodowisk o niskiej zawarto&#x15B;ci tlenu, optymalnych dla ich metabolizmu.
Bakterie acidofilne, takie jak Acidithiobacillus, u&#x142;atwiaj&#x105; obieg &#x17C;elaza w kwa&#x15B;nych, bogatych w tlen &#x15B;rodowiskach. Organizmy te rozwijaj&#x105; si&#x119; przy niskim pH i przyczyniaj&#x105; si&#x119; do przemian &#x17C;elaza poprzez utlenianie Fe&#xB2;&#x207A; do Fe&#xB3;&#x207A;. Ten proces utleniania ma kluczowe znaczenie w &#x15B;rodowiskach takich jak systemy kwa&#x15B;nego drena&#x17C;u kopalnianego.
Obieg manganu w niszach mikrobiologicznych
Gatunki Leptothrix r&#xF3;wnie&#x17C; przyczyniaj&#x105; si&#x119; do obiegu manganu poprzez utlenianie rozpuszczalnych jon&#xF3;w manganu(II) [Mn(II)] do nierozpuszczalnego dwutlenku manganu [MnO&#x2082;], kt&#xF3;ry opada do le&#x17C;&#x105;cych poni&#x17C;ej osad&#xF3;w beztlenowych. W tych warstwach bakterie redukuj&#x105;ce metale, takie jak Geobacter, enzymatycznie redukuj&#x105; dwutlenek manganu z powrotem do Mn(II), zamykaj&#x105;c cykl. Podobnie bakterie fototroficzne w warunkach beztlenowych wykorzystuj&#x105; Fe(II) jako donor elektron&#xF3;w w fotosyntezie anoksygenicznej, podczas gdy fakultatywne beztlenowce, takie jak Shewanella, redukuj&#x105; &#x17C;elazo(III) na drodze szlak&#xF3;w dysymilacyjnych w celu pozyskania energii.
Te procesy mikrobiologiczne wsp&#xF3;lnie utrzymuj&#x105; homeostaz&#x119; &#x17C;elaza i manganu w ekosystemach wodnych, po&#x15B;rednicz&#x105;c w ich dost&#x119;pno&#x15B;ci i rozmieszczeniu wzd&#x142;u&#x17C; granic redoks.

Microbial activity plays a pivotal role in the biogeochemical cycling of iron and manganese, especially at the redox gradients characteristic of ...

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Education

JoVE Core

Microbiology

Mikrobiologia

Unit

Jednostka

Microbial Ecology

Ekologia mikroorganizmów

KEY TERMS AND CONCEPTS

KLUCZOWE TERMINY I POJĘCIA

microbes driving iron and manganese cycles

Microbes drive iron and manganese cycling in aquatic environments by changing these metals between reduced and oxidized forms. These reactions are especially important along redox gradients, where oxygen levels shift across stratified water layers. The microbes use these metals for energy, growth, and structural needs.

In oxygen-rich surface waters, iron is usually present as insoluble ferric iron, Fe(III). Some bacteria release siderophores, which are small organic molecules that bind ferric iron and make it soluble for uptake. After the iron enters the cell, enzymes reduce it to ferrous iron, Fe(II), which is easier for the cell to use.

At the oxic-anoxic interface, bacteria such as Leptothrix oxidize soluble Fe(II) back to Fe(III). This creates extracellular iron oxide sheaths around the cells. The sheaths help keep the cells from becoming encrusted and may also provide support. Magnetotactic bacteria live in this zone too. They build magnetite, Fe3O4, crystals inside the cell. These crystals act like tiny compasses and align with Earth’s magnetic field, helping the bacteria move toward low-oxygen conditions.

Acidophilic bacteria such as Acidithiobacillus also take part in iron cycling. They live in acidic, oxygen-rich environments and oxidize Fe(II) to Fe(III). This activity is important in places such as acid mine drainage systems. In manganese cycling, Leptothrix species oxidize soluble Mn(II) to insoluble manganese dioxide, MnO2. The MnO2 then sinks into anoxic sediments below.

In those sediments, metal-reducing bacteria such as Geobacter reduce manganese dioxide back to Mn(II). That closes the manganese cycle. Other microbes also use iron in special ways. Phototrophic bacteria under anoxic conditions use Fe(II) as an electron donor during anoxygenic photosynthesis. Facultative anaerobes such as Shewanella reduce ferric iron through dissimilatory pathways to gain energy. Together, these microbial processes control where iron and manganese are found in aquatic ecosystems and help maintain their cycling across redox interfaces.

Microbes Driving Iron and Manganese Cycles

microbes-driving-iron-and-manganese-cycles

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key terms and concepts

Learn how microbes move iron and manganese through aquatic environments, from siderophores and magnetite to metal reduction in redox zones.

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microbiology

Microbes Driving Iron and Manganese Cycles

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