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

Anoxygenic phototrophic bacteria that do not generate oxygen as a product of photosynthesis include purple sulfur, purple nonsulfur, green sulfur, and green nonsulfur bacteria.Purple sulfur bacteria belong to several genera in the class Gammaproteobacteria, including Chromatium. They are found predominantly in sulfur-rich meromictic lakes and typically have sulfur granules in the cells.In contrast, purple nonsulfur bacteria, classified into Alpha and Betaproteobacteria, thrive in low-sulfur environments. A key genus is Rhodomicrobium.Both groups of purple bacteria have lamellar intracellular photosynthetic membrane systems and contain bacteriochlorophyll a or b.Green sulfur bacteria belong to the phylum Chlorobi. They contain bacteriochlorophyll c, d, or e, housed in chlorosomes, as seen in the representative species Chlorobaculum tepidum. They thrive in sulfur-rich and deep-sea environments.Green nonsulfur bacteria are classified into the phylum Chloroflexi. Most species, including Chloroflexus aurantiacus, are filamentous and contain bacteriochlorophylls a or c for photosynthesis.

fototrofe bacteriën

Anoxygenic Phototrophic Bacteria

Anoxygene fototrofe bacteri&#235;n vormen een diverse groep micro-organismen die fotosynthese uitvoeren zonder zuurstofproductie. Ze omvatten voornamelijk paarse zwavelbacteri&#235;n, paarse niet-zwavelbacteri&#235;n, groene zwavelbacteri&#235;n en groene niet-zwavelbacteri&#235;n. Deze bacteri&#235;n worden ingedeeld in de lijnages van de Gammaproteobacteria, Alphaproteobacteria, Betaproteobacteria, Chlorobi en Chloroflexi, elk met specifieke fysiologische en ecologische aanpassingen.
Paarse zwavelbacteri&#235;n behoren tot de Gammaproteobacteria en floreren in zwavelrijke, anoxische omgevingen zoals meromictische meren, mariene sedimenten en zoutmoerassen. Ze oxideren waterstofsulfide (H_2S) als elektrondonor voor fotosynthese, waarbij aanvankelijk elementaire zwavel (S_0) wordt geproduceerd en intracellulair opgeslagen, en vervolgens geoxideerd tot sulfaat (SO_4^2-). Representatieve geslachten zijn Chromatium en Thiocapsa. Deze bacteri&#235;n bevatten bacteriochlorofyl a of b en maken gebruik van een Q-type fotosysteem voor lichtopvang.
Paarse niet-zwavelbacteri&#235;n, behorend tot de Alphaproteobacteria en Betaproteobacteria, zijn metabool veelzijdig en gedijen in omgevingen met lage H_2S-concentraties. Ze functioneren typisch als fotoheterotrofen, waarbij ze licht gebruiken als energiebron en organische verbindingen als koolstofbron, maar sommige soorten kunnen ook fotoautotroof groeien met behulp van H_2, lage H_2S-concentraties of Fe^2+. Ze bezitten eveneens Q-type fotosystemen en bevatten bacteriochlorofyl a of b. Bekende geslachten zijn Rhodobacter en Rhodospirillum.
Groene zwavelbacteri&#235;n, geclassificeerd binnen de Chlorobi, zijn strikt ana&#235;robe, niet-motiele fototrofen die H_2S gebruiken als elektrondonor. In tegenstelling tot paarse zwavelbacteri&#235;n slaan zij S_0 extracellulair op en gebruiken zij de omgekeerde citroenzuurcyclus voor CO_2-fixatie. Ze bevatten bacteriochlorofyl c, d of e, opgeslagen in chlorosomen&#8212;unieke lichtopvangstructuren. Chlorobaculum tepidum is een goed bestudeerde soort die groeit in sulfidische omgevingen met minimaal licht.
Groene niet-zwavelbacteri&#235;n, ook wel filamenteuze anoxygene fototrofen genoemd, behoren tot de Chloroflexi. Ze groeien hoofdzakelijk als fotoheterotrofen maar kunnen ook fotoautotrofie uitvoeren met H_2 of H_2S als elektrondonor. Hun fotosynthetisch systeem is een hybride tussen dat van paarse en groene zwavelbacteri&#235;n, met zowel een Q-type fotosysteem als chlorosomen. Chloroflexus aurantiacus is een representatieve soort, vaak aangetroffen in warmwaterbronnen. Thermomicrobium, een verwant niet-fototroof geslacht, is een thermofiel organisme met ongebruikelijke membraanlipiden.
Heliobacteri&#235;n zijn anoxygene fototrofe gram-positieve bacteri&#235;n die behoren tot de stam Firmicutes. Ze bezitten een FeS-type fotosysteem en produceren op unieke wijze bacteriochlorofyl g. Deze bacteri&#235;n groeien fotoheterotroof en gebruiken organische verbindingen zoals pyruvaat, lactaat, acetaat of butyraat. De groep omvat vijf geslachten: Heliobacterium, Heliophilum, Heliorestis, Heliomonas en Heliobacillus. Ze komen voor als staafvormige of filamenteuze cellen, waarbij Heliophilum motiele bundels vormt.
Een andere onderscheidende groep van anoxygene fototrofen is Chloracidobacterium thermophilum, behorend tot de stam Acidobacteria. Deze thermofiele bacterie werd ontdekt in microbi&#235;le matten van thermale bronnen. Ze deelt enkele eigenschappen met groene zwavelbacteri&#235;n, zoals de productie van bacteriochlorofyl a en c in chlorosomen en het gebruik van een FeS-type fotosysteem. In tegenstelling tot groene zwavelbacteri&#235;n is C. thermophilum echter zuurstoftolerant en kan ze aeroob groeien. Ze is een fotoheterotroof organisme dat korteketenvetzuren als koolstofbron gebruikt, maar autotrofe capaciteiten ontbreken.
Deze bacteri&#235;n spelen een essenti&#235;le rol in de wereldwijde zwavel- en koolstofcycli en floreren in diverse ecologische niches met lage zuurstofconcentraties en hoge beschikbaarheid van zwavel.

Fototrofe bacteriën

Anoxygene fototrofe bacteri&#235;n vormen een diverse groep micro-organismen die fotosynthese uitvoeren zonder zuurstofproductie. Ze omvatten voornamelijk ...

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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

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anoxygenic phototrophic bacteria

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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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