Name: sulfur-using bacteria that harvest light
Uploaded: 2025-06-12T09:22:25.000Z
Duration: 1 min 28 s
Channel: JoVE

Les bactéries phototrophes anoxygènes qui ne génèrent pas d’oxygène en tant que produit de la photosynthèse comprennent le soufre violet, le non-soufre violet, le soufre vert et les bactéries vertes non soufrées. Les bactéries soufrées pourpres appartiennent à plusieurs genres de la classe des Gammaprotéobactéries, y compris Chromatium. Ils se trouvent principalement dans les lacs méromictiques riches en soufre et ont généralement des granules de soufre dans les cellules. En revanche, les bactéries violettes non soufrées, classées en alpha et bêtaprotéobactéries, prospèrent dans des environnements à faible teneur en soufre. Un genre clé est Rhodomicrobium. Les deux groupes de bactéries violettes ont des systèmes de membrane photosynthétique intracellulaire lamellaire et contiennent de la bactériochlorophylle a ou b.Les bactéries soufrées vertes appartiennent à l’embranchement des Chlorobi. Ils contiennent de la bactériochlorophylle c, d, ou e, logée dans des chlorosomes, comme on le voit chez l’espèce représentative Chlorobaculum tepidum. Ils prospèrent dans des environnements riches en soufre et en eaux profondes. Les bactéries vertes non soufrées sont classées dans l’embranchement Chloroflexi. La plupart des espèces, y compris Chloroflexus aurantiacus, sont filamenteuses et contiennent des bactériochlorophylles a ou c pour la photosynthèse.

bactéries phototrophes

Anoxygenic Phototrophic Bacteria

Les bact&#233;ries phototrophes anoxyg&#233;niques forment un groupe diversifi&#233; de micro-organismes capables d&#8217;effectuer la photosynth&#232;se sans production d&#8217;oxyg&#232;ne. Elles comprennent principalement les bact&#233;ries pourpres sulfureuses, les bact&#233;ries pourpres non sulfureuses, les bact&#233;ries vertes sulfureuses et les bact&#233;ries vertes non sulfureuses. Ces bact&#233;ries appartiennent aux lign&#233;es des Gammaproteobacteria, Alphaproteobacteria, Betaproteobacteria, Chlorobi et Chloroflexi, chacune pr&#233;sentant des adaptations physiologiques et &#233;cologiques distinctes.
Les bact&#233;ries pourpres sulfureuses, class&#233;es parmi les Gammaproteobacteria, prosp&#232;rent dans des environnements anoxiques riches en soufre, tels que les lacs m&#233;romictiques, les s&#233;diments marins et les marais salants. Elles oxydent le sulfure d&#8217;hydrog&#232;ne (H_2S) comme donneur d&#8217;&#233;lectrons pour la photosynth&#232;se, produisant initialement du soufre &#233;l&#233;mentaire (S^0) stock&#233; dans les cellules, puis l&#8217;oxydant en sulfate (SO_4^2-). Les genres repr&#233;sentatifs incluent Chromatium et Thiocapsa. Ces bact&#233;ries contiennent de la bact&#233;riochlorophylle a ou b et utilisent un photosyst&#232;me de type Q pour la capture de la lumi&#232;re.
Les bact&#233;ries pourpres non sulfureuses, pr&#233;sentes chez les Alphaproteobacteria et Betaproteobacteria, sont m&#233;taboliquement polyvalentes et se d&#233;veloppent dans des environnements pauvres en H_2S. Elles fonctionnent typiquement comme photo-h&#233;t&#233;rotrophes, utilisant la lumi&#232;re comme source d&#8217;&#233;nergie et des compos&#233;s organiques comme source de carbone, mais certaines esp&#232;ces peuvent cro&#238;tre de mani&#232;re photo-autotrophe en utilisant H_2, de faibles concentrations de H_2S ou Fe^2+. Elles poss&#232;dent &#233;galement des photosyst&#232;mes de type Q et contiennent de la bact&#233;riochlorophylle a ou b. Les genres notables incluent Rhodobacter et Rhodospirillum.
Les bact&#233;ries vertes sulfureuses, class&#233;es dans le phylum Chlorobi, sont des phototrophes strictement ana&#233;robies et non mobiles, utilisant H_2S comme donneur d&#8217;&#233;lectrons. Contrairement aux bact&#233;ries pourpres sulfureuses, elles stockent le soufre &#233;l&#233;mentaire &#224; l&#8217;ext&#233;rieur des cellules et fixent le CO_2 via le cycle de l&#8217;acide citrique invers&#233;. Elles contiennent de la bact&#233;riochlorophylle c, d ou e, localis&#233;e dans des structures sp&#233;cialis&#233;es appel&#233;es chlorosomes. Chlorobaculum tepidum est une esp&#232;ce bien &#233;tudi&#233;e qui vit dans des environnements sulfid&#233;s &#224; faible luminosit&#233;.
Les bact&#233;ries vertes non sulfureuses, ou phototrophes anoxyg&#233;niques filamenteuses, appartiennent aux Chloroflexi. Elles croissent principalement en tant que photo-h&#233;t&#233;rotrophes mais peuvent aussi r&#233;aliser la photo-autotrophie en utilisant H_2 ou H_2S. Leur syst&#232;me photosynth&#233;tique est hybride, combinant un photosyst&#232;me de type Q et des chlorosomes. Chloroflexus aurantiacus est une esp&#232;ce repr&#233;sentative que l&#8217;on trouve couramment dans les sources chaudes. Thermomicrobium, un genre apparent&#233; non phototrophe, est un thermophile aux lipides membranaires inhabituels.
Les h&#233;liobact&#233;ries sont des bact&#233;ries phototrophes anoxyg&#233;niques &#224; Gram positif appartenant au phylum Firmicutes. Elles poss&#232;dent un photosyst&#232;me de type FeS et produisent de mani&#232;re unique de la bact&#233;riochlorophylle g. Ces bact&#233;ries se d&#233;veloppent en photo-h&#233;t&#233;rotrophie, utilisant des compos&#233;s organiques tels que le pyruvate, le lactate, l&#8217;ac&#233;tate ou le butyrate. Le groupe comprend cinq genres : Heliobacterium, Heliophilum, Heliorestis, Heliomonas et Heliobacillus. Elles se pr&#233;sentent sous forme de cellules en b&#226;tonnets ou filamenteuses, Heliophilum formant des faisceaux mobiles.
Un autre groupe distinct de phototrophes anoxyg&#233;niques, Chloracidobacterium thermophilum, appartient au phylum Acidobacteria. Cette bact&#233;rie thermophile a &#233;t&#233; d&#233;couverte dans les tapis microbiens des sources thermales. Elle partage des caract&#233;ristiques avec les bact&#233;ries vertes sulfureuses, telles que la production de bact&#233;riochlorophylle a et c dans des chlorosomes, et l&#8217;utilisation d&#8217;un photosyst&#232;me de type FeS. Toutefois, &#224; la diff&#233;rence des bact&#233;ries vertes sulfureuses, C. thermophilum tol&#232;re l&#8217;oxyg&#232;ne et peut cro&#238;tre en conditions a&#233;robies. C&#8217;est une photo-h&#233;t&#233;rotrophe qui utilise les acides gras &#224; cha&#238;ne courte comme source de carbone, mais ne poss&#232;de pas de capacit&#233;s autotrophes.
Ces bact&#233;ries jouent un r&#244;le essentiel dans les cycles globaux du soufre et du carbone, prosp&#233;rant dans des niches &#233;cologiques vari&#233;es caract&#233;ris&#233;es par de faibles concentrations en oxyg&#232;ne et une forte disponibilit&#233; en soufre.

Bactéries phototrophes

Les bact&#233;ries phototrophes anoxyg&#233;niques forment un groupe diversifi&#233; de micro-organismes capables d&#8217;effectuer la photosynth&#232;se ...

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Microbial Diversity

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KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

sulfur-using bacteria that harvest light

Anoxygenic phototrophic bacteria are light-harvesting bacteria that do not release oxygen during photosynthesis. They include purple sulfur bacteria, purple nonsulfur bacteria, green sulfur bacteria, green nonsulfur bacteria, heliobacteria, and Chloracidobacterium thermophilum. These groups belong to the Gammaproteobacteria, Alphaproteobacteria, Betaproteobacteria, Chlorobi, Chloroflexi, Firmicutes, and Acidobacteria lineages, and each group has its own habitat and way of using light.

Purple sulfur bacteria live in sulfur-rich, oxygen-free settings such as meromictic lakes, marine sediments, and salt marshes. They use hydrogen sulfide as an electron donor for photosynthesis. They first make elemental sulfur, store it inside the cell, and later oxidize it to sulfate. Common examples include Chromatium and Thiocapsa, and these bacteria contain bacteriochlorophyll a or b and use a Q-type photosystem.

Purple nonsulfur bacteria belong to the Alphaproteobacteria and Betaproteobacteria and are more flexible in how they live. They usually act as photoheterotrophs, which means they use light for energy and organic compounds for carbon. Some species can also grow photoautotrophically with hydrogen, low levels of hydrogen sulfide, or iron(II). Rhodobacter and Rhodospirillum are well-known genera, and these bacteria also contain bacteriochlorophyll a or b and Q-type photosystems.

Green sulfur bacteria are strict anaerobes, which means they grow only without oxygen, and they do not move. They use hydrogen sulfide as an electron donor, but unlike purple sulfur bacteria, they store elemental sulfur outside the cell. They fix carbon dioxide through the reverse citric acid cycle. Their light-harvesting structures are chlorosomes, and they contain bacteriochlorophyll c, d, or e. Chlorobaculum tepidum is a well-studied species that can live in sulfidic places with very little light.

Green nonsulfur bacteria, also called filamentous anoxygenic phototrophs, belong to Chloroflexi. They are mainly photoheterotrophs, but they can also do photoautotrophy with hydrogen or hydrogen sulfide. Their photosynthetic system combines features seen in purple and green sulfur bacteria. They have a Q-type photosystem and chlorosomes, and Chloroflexus aurantiacus is a common example from hot springs. Thermomicrobium is a related nonphototrophic genus with unusual membrane lipids.

Heliobacteria are gram-positive anoxygenic phototrophs in the phylum Firmicutes. They use an FeS-type photosystem and make bacteriochlorophyll g, which makes them different from the purple and green groups. They grow photoheterotrophically and use organic compounds such as pyruvate, lactate, acetate, or butyrate. The group includes Heliobacterium, Heliophilum, Heliorestis, Heliomonas, and Heliobacillus. These cells may be rod-shaped or filamentous, and Heliophilum can form motile bundles.

Chloracidobacterium thermophilum is another anoxygenic phototroph from the phylum Acidobacteria. It was discovered in microbial mats of thermal springs. It shares features with green sulfur bacteria because it makes bacteriochlorophyll a and c in chlorosomes and uses an FeS-type photosystem. However, it can tolerate oxygen and can grow aerobically. It is a photoheterotroph that uses short-chain fatty acids as a carbon source, but it does not have autotrophic growth. Together, these bacteria help drive sulfur and carbon cycling in low-oxygen, sulfur-rich environments.

Sulfur-Using Bacteria That Harvest Light

three-domain system of life

How rRNA Reshaped Life's Domains

Ribosomal RNA, or rRNA, changed how scientists classify life. Sequence analysis showed three major groups of cells: eukaryotes, bacteria, and archaea. In 1978, Carl R. Woese proposed domains as a taxonomic level above kingdoms to separate these groups. Woese also showed that archaea and bacteria are not the same, even though they can look similar. The three domains differ in rRNA, membrane lipid structure, transfer RNA, and sensitivity to antibiotics. These differences helped scientists build...

microbial classification system

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Microbial classification organizes bacteria and archaea into ranked groups based on shared traits and evolutionary relationships. Scientists use phenotypic similarities, which are visible or measurable traits, and genotypic data, which comes from genetic information. The result is a hierarchy that helps place each organism in a clear taxonomic order. The ranking system starts with species and moves upward through genus, family, order, class, and finally domain. A species can include one or...

methods of classification and identification

methods-of-classification-and-identification

Bacterial ID Through Lab Tests

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modern molecular taxonomy

DNA Tools for Identifying Bacteria

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applications of molecular taxonomy

Molecular Taxonomy in Bacterial Research

Molecular taxonomy in bacterial research uses DNA sequencing and DNA fingerprinting to classify bacteria more precisely. These molecular tools help scientists study bacterial diversity, evolutionary relationships, and ecological roles. They have changed how researchers identify and compare bacteria in both health and environmental studies. One major use of molecular taxonomy is resolving taxonomic ambiguities, or unclear classification cases. It can separate closely related bacteria that were...

bacterial phylum proteobacteria

Proteobacteria Classes and Their Key Roles

Proteobacteria are a large and diverse phylum of Gram-negative bacteria. They have an outer membrane that contains lipopolysaccharides. Many of them use different ways to get energy, including phototrophy, chemolithotrophy, and heterotrophy. They live in soil, water, and host-associated environments. This phylum is divided into six classes: Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Epsilonproteobacteria, and Zetaproteobacteria. Each class includes...

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Chlamydiae Life Cycle and Host Infection

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bacterial phylum planctomycetes 

Planctomycetes Cell Structure and Life Cycle

Planctomycetes are a group of gram-negative bacteria known for unusual cell structures and a distinctive life cycle. They are mainly placed in two orders, Planctomycetales and Brocadiales. Many cells show stalks or other appendages and often appear in rosette groups. A key feature of these bacteria is their cell envelope. Planctomycetes have an S-layer, a surface layer that is relatively uncommon in bacteria. They also divide by budding, which is different from the simple cell split seen in...

bacterial phylum verrucomicrobiota

Verrucomicrobiota Cell Structure and Traits

Verrucomicrobiota are a bacterial phylum with several recognized orders, and most species belong to Verrucomicrobiotales. Many members are aerobic or facultatively aerobic, which means they can use oxygen but may also grow without it. They can also ferment sugars. One exception is the genus Methylacidiphilum, which contains aerobic methanotrophs, bacteria that use methane and oxygen. These bacteria live in many different places. They are found in freshwater, marine habitats, forest soils, and...

bacterial phylum spirochaetes

Spirochete Shape, Motion, and Disease

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bacterial phylum cyanobacteria

Cyanobacteria and Oxygenic Photosynthesis

Cyanobacteria are oxygenic, phototrophic bacteria that helped change Earth&amp;#8217;s atmosphere from low in oxygen to oxygen-rich billions of years ago. They are also very diverse in shape and size. Some are unicellular, while others grow as filaments. Cell size can range from 0.5 µm to 100 µm. Scientists group cyanobacteria into five major types. Chroococcales are unicellular and divide by binary fission. Pleurocapsales are also unicellular, but they divide by multiple fission.

bacterial phylum actinobacteria

Actinobacteria: Soil Bacteria and Cheese

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bacterial phylum firmicutes

Firmicutes: Bacteria, Fermentation, and Spores

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bacterial phylum bacteroidota

Gut and Environment Bacteria in Bacteroidota

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anoxygenic phototrophic bacteria

Anoxygenic phototrophic bacteria are light-harvesting bacteria that do not release oxygen during photosynthesis. They include purple sulfur bacteria, purple nonsulfur bacteria, green sulfur bacteria, green nonsulfur bacteria, heliobacteria, and Chloracidobacterium thermophilum. These groups belong to the Gammaproteobacteria, Alphaproteobacteria, Betaproteobacteria, Chlorobi, Chloroflexi, Firmicutes, and Acidobacteria lineages, and each group has its own habitat and way of using light. Purple...

hyperthermophilic bacteria

Heat-Loving Bacteria and Their Enzymes

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bacterial phylum tenericutes

Mycoplasmas and Wall-Less Bacteria

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other unique bacteria

Magnetotactic and DNA-Resistant Bacteria

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diversity of archaea i

Archaea Extremes: Euryarchaeota

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diversity of archaea ii

New Archaea Phyla and Their Roles

Archaea are one of the three domains of life, and their diversity includes species that live in both extreme and moderate environments. For a long time, most known archaea were grouped into two major phyla: Euryarchaeota and Crenarchaeota. Recent molecular studies have added three more phyla to this picture: Thaumarchaeota, Nanoarchaeota, and Korarchaeota. Thaumarchaeota are mesophilic archaea, which means they live in moderate conditions. They are found in soils, lakes, and marine regions. A...

diversity of archaea iii

Crenarchaeota in Extreme Hot Springs

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diversity of archaea iv

How Hyperthermophilic Archaea Survive Heat

Hyperthermophilic archaea are heat-loving extremophiles that live at temperatures above 80°C. They are often found in hydrothermal vents and volcanic soils, where the heat can be higher than the boiling point of water. At these temperatures, the proteins, membranes, and DNA of most organisms would break down. These archaea survive because their cell membranes are built differently. Their membranes contain a monolayer of biphytanyl tetraether lipids, which helps resist thermal damage. This...

overview of fungi

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fungal group zygomycota

Zygomycota: Spores, Hyphae, and Roles

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fungal phylum microsporidia

Microsporidia Spores and Host Infection

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fungal phylum ascomycota

Ascomycota: Sac Fungi and Their Spore Cycle

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fungal phylum basidiomycota

Basidiomycota: Mushrooms, Spores, and Ecological Roles

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overview of algae

Algae Structure, Habitats, and Reproduction

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red algae

Red Algae Pigments, Shapes, and Uses

Red algae are phototrophic organisms found mostly in marine environments. Some species also live in freshwater or on land. They may be unicellular or multicellular, and some multicellular forms grow large enough to be seen easily. These algae contain chlorophyll a, but their chloroplasts do not contain chlorophyll b. Instead, they use phycobiliproteins, which are light-harvesting pigments like those found in cyanobacteria. The red color seen in many species comes from phycoerythrin, an...

green algae

Green Algae: Forms, Habitats, and Roles

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other algae

Stramenopile Algae: Diatoms, Golden, Brown

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overview of protists

Protist Diversity, Movement, and Survival

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diversity of protists i

Excavata Protists and Their Adaptations

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diversity of protists ii

Alveolates: Ciliates, Dinoflagellates, Apicomplexans

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diversity of protists iii

Rhizaria: Pseudopods, Tests, and Skeletons

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diversity of protists iv

Amoebozoa: Movement and Life Cycles

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key terms and concepts

Explore how anoxygenic phototrophic bacteria use light without making oxygen, from purple and green sulfur bacteria to heliobacteria and thermal spring species.

Sulfur-Using Bacteria That Harvest Light | 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-Using Bacteria That Harvest Light

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