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

As bactérias fototróficas anoxigênicas que não geram oxigênio como produto da fotossíntese incluem enxofre roxo, enxofre roxo, enxofre verde e bactérias verdes sem enxofre. As bactérias sulfurosas roxas pertencem a vários gêneros da classe Gammaproteobacteria, incluindo Chromatium. Eles são encontrados predominantemente em lagos meromíticos ricos em enxofre e normalmente têm grânulos de enxofre nas células. Em contraste, as bactérias roxas sem enxofre, classificadas em alfa e betaproteobactérias, prosperam em ambientes com baixo teor de enxofre. Um gênero chave é Rhodomicrobium. Ambos os grupos de bactérias roxas têm sistemas de membrana fotossintética intracelular lamelar e contêm bacterioclorofila a ou b.As bactérias sulfurosas verdes pertencem ao filo Chlorobi. Eles contêm bacterioclorofila c, d, ou e, alojados em clorossomos, como visto nas espécies representativas Chlorobaculum tepidum. Eles prosperam em ambientes ricos em enxofre e em alto mar. As bactérias verdes não sulfurosas são classificadas no filo Chloroflexi. A maioria das espécies, incluindo Chloroflexus aurantiacus, são filamentosas e contêm bacterioclorofilas a ou c para a fotossíntese.

bactérias fototróficas

Anoxygenic Phototrophic Bacteria

As bact&#233;rias fototr&#243;ficas anoxig&#234;nicas s&#227;o um grupo diverso de microrganismos que realizam fotoss&#237;ntese sem produzir oxig&#234;nio. Incluem principalmente bact&#233;rias p&#250;rpuras sulfurosas, p&#250;rpuras n&#227;o sulfurosas, verdes sulfurosas e verdes n&#227;o sulfurosas. Essas bact&#233;rias est&#227;o classificadas nas linhagens Gammaproteobacteria, Alphaproteobacteria, Betaproteobacteria, Chlorobi e Chloroflexi, cada uma com adapta&#231;&#245;es fisiol&#243;gicas e ecol&#243;gicas distintas.
As bact&#233;rias p&#250;rpuras sulfurosas pertencem &#224;s Gammaproteobacteria e prosperam em ambientes an&#243;xicos ricos em enxofre, como lagos merom&#237;ticos, sedimentos marinhos e p&#226;ntanos salinos. Oxidam sulfeto de hidrog&#234;nio (H_2S) como doador de el&#233;trons na fotoss&#237;ntese, produzindo inicialmente enxofre elementar (S_0), que &#233; armazenado no interior das c&#233;lulas, e posteriormente oxidado a sulfato (SO_4^2-). G&#234;neros representativos incluem Chromatium e Thiocapsa. Essas bact&#233;rias cont&#234;m bacterioclorofila a ou b e utilizam um fotossistema do tipo Q para captura de luz.
As bact&#233;rias p&#250;rpuras n&#227;o sulfurosas, encontradas em Alphaproteobacteria e Betaproteobacteria, s&#227;o metabolicamente vers&#225;teis e prosperam em ambientes com baixos n&#237;veis de H_2S. Tipicamente funcionam como fotoheter&#243;trofas, usando luz como fonte de energia e compostos org&#226;nicos como fonte de carbono, embora algumas esp&#233;cies possam crescer fotoautotroficamente utilizando H_2, baixos n&#237;veis de H_2S ou Fe^2+. Tamb&#233;m possuem fotossistemas do tipo Q e cont&#234;m bacterioclorofila a ou b. G&#234;neros not&#225;veis incluem Rhodobacter e Rhodospirillum.
As bact&#233;rias verdes sulfurosas, classificadas em Chlorobi, s&#227;o fototr&#243;ficas anaer&#243;bias estritas e im&#243;veis que utilizam H_2S como doador de el&#233;trons. Ao contr&#225;rio das bact&#233;rias p&#250;rpuras sulfurosas, armazenam o S_0 fora das c&#233;lulas e utilizam o ciclo reverso do &#225;cido c&#237;trico para a fixa&#231;&#227;o de CO_2. Cont&#234;m bacterioclorofila c, d ou e, localizada em clorossomos&#8212;estruturas &#250;nicas de captura de luz. Chlorobaculum tepidum &#233; uma esp&#233;cie bastante estudada que prospera em ambientes sulfidr&#237;cos com pouca luz.
As bact&#233;rias verdes n&#227;o sulfurosas, ou fototr&#243;ficas anoxig&#234;nicas filamentosas, pertencem &#224; Chloroflexi. Crescem principalmente como fotoheter&#243;trofas, mas tamb&#233;m podem realizar fotoautotrofia usando H_2 ou H_2S. Seu sistema fotossint&#233;tico &#233; h&#237;brido entre os das bact&#233;rias p&#250;rpuras e verdes sulfurosas, contendo tanto fotossistema do tipo Q quanto clorossomos. Chloroflexus aurantiacus &#233; uma esp&#233;cie representativa, comumente encontrada em fontes termais. Thermomicrobium, um g&#234;nero n&#227;o fototr&#243;fico relacionado, &#233; um term&#243;filo com lip&#237;dios de membrana incomuns.
As heliobact&#233;rias s&#227;o bact&#233;rias Gram-positivas fototr&#243;ficas anoxig&#234;nicas pertencentes ao filo Firmicutes. Possuem um fotossistema do tipo FeS e produzem unicamente bacterioclorofila g. Crescem como fotoheter&#243;trofas, utilizando compostos org&#226;nicos como piruvato, lactato, acetato ou butirato. O grupo inclui cinco g&#234;neros: Heliobacterium, Heliophilum, Heliorestis, Heliomonas e Heliobacillus. Apresentam-se como c&#233;lulas em bastonete ou filamentosas, com Heliophilum formando agregados m&#243;veis.
Outro grupo distinto de fototr&#243;ficas anoxig&#234;nicas &#233; Chloracidobacterium thermophilum, pertencente ao filo Acidobacteria. Esta bact&#233;ria termof&#237;lica foi descoberta em mantos microbianos de fontes termais. Compartilha algumas caracter&#237;sticas com as bact&#233;rias verdes sulfurosas, como a produ&#231;&#227;o de bacterioclorofila a e c em clorossomos e o uso de um fotossistema do tipo FeS. No entanto, ao contr&#225;rio das verdes sulfurosas, C. thermophilum tolera oxig&#234;nio e pode crescer aerobicamente. &#201; uma fotoheter&#243;trofa que utiliza &#225;cidos graxos de cadeia curta como fonte de carbono, mas n&#227;o possui capacidades autotr&#243;ficas.
Essas bact&#233;rias desempenham pap&#233;is essenciais nos ciclos globais do enxofre e do carbono, prosperando em nichos ecol&#243;gicos diversos com baixa concentra&#231;&#227;o de oxig&#234;nio e alta disponibilidade de enxofre.

Bactérias fototróficas

As bact&#233;rias fototr&#243;ficas anoxig&#234;nicas s&#227;o um grupo diverso de microrganismos que realizam fotoss&#237;ntese sem produzir ...

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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

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...

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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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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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bacterial phylum planctomycetes 

Planctomycetes Cell Structure and Life Cycle

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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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diversity of archaea i

Archaea Extremes: Euryarchaeota

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diversity of archaea ii

New Archaea Phyla and Their Roles

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diversity of archaea iii

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diversity of archaea iv

How Hyperthermophilic Archaea Survive Heat

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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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Algae Structure, Habitats, and Reproduction

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red algae

Red Algae Pigments, Shapes, and Uses

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green algae

Green Algae: Forms, Habitats, and Roles

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other algae

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overview of protists

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diversity of protists i

Excavata Protists and Their Adaptations

Excavata protists show many different ways of living, from photosynthesis to parasitism. This group includes organisms that can use chemical energy, light, or both. Some also live in low-oxygen, or anaerobic, environments where they survive without normal oxygen-based metabolism. Among the main Excavata groups are diplomonads and parabasalids. These are flagellated protists, meaning they move with whip-like tails, and they lack mitochondria and chloroplasts. They often live in anoxic habitats,...

diversity of protists ii

Alveolates: Ciliates, Dinoflagellates, Apicomplexans

Alveolates are protists with tiny sacs called alveoli beneath the cell membrane. These sacs may help control water balance by limiting how much water moves in and out of the cell. In dinoflagellates, alveoli may also act like armor plates. The three main alveolate groups are ciliates, dinoflagellates, and apicomplexans. Ciliates move with cilia, which are short hair-like structures that can cover the whole cell or appear in rows or tufts. One well-known ciliate is Paramecium, which uses cilia...

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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