Name: sulfur cycling through microbial reactions
Uploaded: 2026-03-12T13:57:43.000Z
Duration: 1 min 29 s
Channel: JoVE

Anorganischer Schwefel zirkuliert durch die Umwelt als Sulfat, elementarer Schwefel und Schwefel.Vulkane und hydrothermale Quellen stoßen Schwefelgase wie Schwefelwasserstoff aus und leisten so wichtige Beiträge zum Schwefelkreislauf.Zum Beispiel wandeln sulfatreduzierende Bakterien in anoxischen, organisch reichen Umgebungen nahe hydrothermalen Quellen Sulfat hauptsächlich in Schwefelwasserstoff um.Dieses Gas, das für die meisten Lebensformen giftig ist, wird von verschiedenen Mikroorganismen in weniger schädliche Sulfate oder elementaren Schwefel umgewandelt.Unter sauerstoffreichen Bedingungen wandeln schwefeloxidierende Bakterien wie Thiobacillus Schwefelwasserstoff in Schwefel oder Sulfat um, wobei manchmal Schwefelsäure entsteht und der lokale pH-Wert sinkt.Grüne und violette Schwefelbakterien hingegen wandeln Sulfid in Schwefelkörner um, die Thiomargarita und ähnliche Mikroben weiter zu Sulfat oxidieren.Elementarer Schwefel kann durch spezialisierte anaerbe Bakterien und Archaeen wieder zu Sulfid umgewandelt werden.Neben anorganischen Umwandlungen bilden Meeresalgen Dimethylsulfid, eine flüchtige organische Schwefelverbindung, die in der Atmosphäre in Aerosole umgewandelt wird, die die Wolkenbildung fördern und das Erdklima regulieren.

mikroben und der schwefelkreislauf

Microbes and the Sulfur Cycle

Schwefel ist ein lebenswichtiges Element in den biogeochemischen Systemen der Erde. Es durchläuft verschiedene anorganische Zustände, darunter Sulfat (SO₄²⁻), elementaren Schwefel (S⁰) und Sulfid (S²⁻). Abiotische und biologische Mechanismen in oxischen und anoxischen Umgebungen vermitteln diese Transformationen in detailreicher Form. Sulfat, die am stärksten oxidierte Form von Schwefel, wird überwiegend in Gesteinen, marinen Sedimenten und ozeanischen Gewässern gespeichert und dient als langfristiges Reservoir im globalen Schwefelkreislauf.In oxischen Umgebungen katalysieren chemolithoautotrophe Bakterien wie Thiobacillus spp. die Oxidation von reduzierten Schwefelverbindungen. Sulfid (H₂S), das aus vulkanischer Ausgasung oder hydrothermalen Emissionen gewonnen wird, wird biologisch zu elementarem Schwefel und Sulfat oxidiert. Umgekehrt führen unter anoxischen Bedingungen sulfatreduzierende Bakterien (SRB) wie Desulfovibrio spp. dissimilatorische Sulfatreduktion durch. Dieser anaerob Prozess reduziert Sulfat über Sulfit (SO₃²⁻) als wichtiges Zwischenprodukt zu Sulfid, oft in Verbindung mit organischer Kohlenstoffoxidation.Anoxygenhaltige Phototrophe, darunter grüne und violette Schwefelbakterien, oxidieren Sulfid zu intrazellulären Schwefelgranulaten. Diese Körner werden von großen chemolithotropen Bakterien wie Thiomargarita-Arten weiter zu Sulfat oxidiert, die durch die Freisetzung von Protonen während der Oxidation zur Versauerung beitragen. In hydrothermalen Quellökosystemen nutzen schwefeloxidierende Chemoautotrophe Energie aus Schwefel, um Kohlendioxid zu fixieren und so komplexe mikrobielle und faunische Gemeinschaften in Tiefseelebensräumen zu unterstützen.Marine Phytoplankton setzt Dimethylsulfoniopropionat (DMSP) frei, um den osmotischen Druck zu regulieren. Die bakterielle Spaltung von DMSP liefert Dimethylsulfid (DMS), eine flüchtige Verbindung, die in die Atmosphäre gelangt. Die Photooxidation von DMS erzeugt Sulfataerosole, die die Wolkenkondensation und die atmosphärische Schwefelablagerung auf terrestrische Ökosysteme beeinflussen. Letztlich assimilieren und reduzieren Pflanzen und Mikroben dieses Sulfat, während sie schwefelhaltige Aminosäuren wie Cystein und Methionin synthetisieren, wodurch der Zyklus abgeschlossen wird.

Mikroben und der Schwefelkreislauf

Sulfur is a vital element in Earth's biogeochemical systems. It transitions through various inorganic states, including sulfate (SO&#8324;&#178;&#8315;), ...

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Education

Lehre

JoVE Core

Microbiology

Mikrobiologie

Unit

Einheit

Microbial Ecology

Mikrobielle Ökologie

KEY TERMS AND CONCEPTS

ZENTRALE BEGRIFFE UND KONZEPTE

sulfur cycling through microbial reactions

Sulfur cycling depends on microbial reactions that move sulfur through rocks, water, soil, and the air. In Earth systems, sulfur shifts among inorganic forms such as sulfate, elemental sulfur, and sulfide. These changes happen through both abiotic processes and biological activity in oxic and anoxic environments.

Sulfate is the most oxidized form of sulfur. It is stored mainly in rocks, marine sediments, and ocean water, where it acts as a long-term reservoir in the global sulfur cycle. In oxygen-rich settings, chemolithoautotrophic bacteria such as Thiobacillus spp. oxidize reduced sulfur compounds.

Sulfide, often present as H2S, can come from volcanic outgassing or hydrothermal emissions. Microbes can oxidize this sulfide into elemental sulfur and then into sulfate. In oxygen-free environments, sulfate-reducing bacteria such as Desulfovibrio spp. carry out dissimilatory sulfate reduction, which converts sulfate to sulfide through sulfite as an intermediate and is often linked to organic carbon oxidation.

Some microbes use sulfur in light-filled but low-oxygen habitats. Green and purple sulfur bacteria, which are anoxygenic phototrophs, oxidize sulfide and store the sulfur as intracellular granules. Large chemolithotrophic bacteria such as Thiomargarita spp. can then oxidize these granules further to sulfate. This process releases protons and can make the surrounding environment more acidic.

Sulfur cycling also powers life at hydrothermal vents. There, sulfur-oxidizing chemoautotrophs use energy from sulfide to fix carbon dioxide. Their activity supports complex microbial and animal communities in deep-sea ecosystems.

Sulfur also moves through the atmosphere. Marine phytoplankton release dimethylsulfoniopropionate, or DMSP, to help control osmotic pressure. Bacteria break DMSP down into dimethylsulfide, or DMS, a volatile gas that enters the atmosphere. Sunlight then photooxidizes DMS into sulfate aerosols, which affect cloud formation and sulfur deposition on land. Plants and microbes take up this sulfate and reduce it while making sulfur-containing amino acids such as cysteine and methionine, completing the cycle.

Sulfur Cycling Through Microbial Reactions

sulfur-cycling-through-microbial-reactions

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key terms and concepts

Explore how microbes move sulfur through sulfate, sulfide, and sulfur granules in oxic, anoxic, and marine environments across the sulfur cycle.

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microbiology

Sulfur Cycling Through Microbial Reactions

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