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

גופרית אנאורגנית נעה בסביבה כסולפט, גופרית יסודית וסולפיד.הרי געש ופתחי הידרותרמיים פולטים גזי גופרית כמו מימן גופריתי, ותורמים תרומה חיונית למחזור הגופרית.לדוגמה, בסביבות אנוקסיות ועשירות באורגניזם סמוך לפתחים הידרותרמיים, חיידקים מפחיתים סולפט ממירים סולפט בעיקר למימן גופריתי.גז זה, רעיל לרוב יצורי החיים, מומר על ידי מיקרואורגניזמים שונים לסולפט פחות מזיק או גופרית יסודית.בתנאים עשירים בחמצן, חיידקים מחמצנים גופרית כמו תיובצילוס ממירים מימן גופריתי לגופרית או סולפט, לעיתים יוצרים חומצה גופרתית ומורידים את ה-pH המקומי.מצד שני, חיידקי גופרית ירוקים וסגולים ממירים סולפיד לגרגירי גופרית, אותם טיומרגריטה ומיקרובים דומים מחמצנים עוד יותר לסולפט.גופרית יסודית יכולה להיות מופחתת חזרה לגופרית על ידי חיידקים אנאירוביים מיוחדים וארכיאה.בנוסף לטרנספורמציות אנאורגניות, אצות ימיות יוצרות דימתיל סולפיד, תרכובת גופרית אורגנית נדיפה, המומרת באטמוספירה לאירוסולים המעודדים היווצרות עננים ומסייעים בוויסות אקלים כדור הארץ.

מיקרובים ומחזור הגופרית

Microbes and the Sulfur Cycle

גופרית היא יסוד חיוני במערכות הביוגאוכימיות של כדור הארץ. הוא עובר דרך מצבים אנאורגניים שונים, כולל סולפט (SO₄²⁻), גופרית יסודית (S⁰) וסולפיד (S²⁻). מנגנונים אביוטיים וביולוגיים בסביבות חמצניות ואנוקסיות מתווכים באופן מורכב את הטרנספורמציות הללו. סולפט, הצורה המחוסנת ביותר של גופרית, מאוחסנת בעיקר בסלעים, משקעים ימיים ומימי אוקיינוס, ופועלת כמאגר ארוך טווח במחזור הגופרית העולמי.בסביבות חמצניות, חיידקים כימוליטואוטוטרופיים כמו Thiobacillus spp. מזרזים את החמצון של תרכובות גופרית מוקטנות. גופרית (H₂S), שמקורה בפליטת גזים געשיים או פליטות הידרותרמיות, מחומצנת ביולוגית לגופרית וסולפט יסודיים. לעומת זאת, במצבים אנוקסיים, חיידקים מפחיתי סולפט (SRB) כמו Desulfovibrio spp. מבצעים הפחתת סולפט דיסימילטיבית. תהליך אנאירובי זה מפחית את הסולפט לסולפיד באמצעות סולפיט (SO₃²⁻) כאמצעי מרכזי, לעיתים קרובות בשילוב עם חמצון פחמן אורגני.פוטוטרופיים חסרי חמצן, כולל חיידקי גופרית ירוקה וסגולה, מחמצנים סולפיד לגרגירי גופרית תוך-תאיים. גרגרים אלו מחומצנים עוד יותר לסולפט על ידי חיידקים כימוליטוטרופיים גדולים כמו טיומרגריטה spp., התורמים לחמצון על ידי שחרור פרוטונים במהלך החמצון. במערכות אקולוגיות של פתחי מים הידרותרמיים, כימאוטוטרופים מחמצנים גופרית מנצלים אנרגיה מהגופרת כדי לקבע פחמן דו-חמצני, ותומכים בקהילות מיקרוביאליות ובעלי חיים מורכבות בבתי גידול עמוקים בים.פיטופלנקטון ימי משחרר דימתילסולפוניופרופיונאט (DMSP) כדי לווסת את הלחץ האוסמוטי. חיתוך חיידקי של DMSP יוצר דימתילסולפיד (DMS), תרכובת נדיפה שנכנסת לאטמוספירה. פוטואוקסידציה של DMS מייצרת אירוסולים סולפטיים, המשפיעים על עיבוי עננים והצטברות גופרית אטמוספרית במערכות אקולוגיות יבשתיות. בסופו של דבר, צמחים ומיקרובים סופגים ומפחיתים סולפט זה תוך סינתזה של חומצות אמינו המכילות גופרית כמו ציסטאין ומתיונין, ומשלימים את המחזור.

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

JoVE Core

Microbiology

מיקרוביולוגיה

Unit

יחידה

Microbial Ecology

אקולוגיה מיקרוביאלית

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

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

introduction to microbial ecology

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ecological niche

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methods to assess microbial communities

Measuring Microbial Diversity and Activity

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the winogradsky column

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microbial interactions: competition

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microbial interactions: parasitism

Microbial Parasites and Host Dependence

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microbe-plant interactions

How Plant Microbes Affect Growth

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microbes and the carbon cycle

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microbes and methanogenesis

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microbes and the nitrogen cycle

Microbial Steps in the Nitrogen Cycle

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microbes and the sulfur cycle

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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.

Sulfur Cycling Through Microbial Reactions | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

Sulfur Cycling Through Microbial Reactions

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