Name: how chemolithotrophs make atp
Uploaded: 2025-06-12T09:35:21.000Z
Duration: 1 min 15 s
Channel: JoVE

Os quimiolitotróficos obtêm energia oxidando compostos inorgânicos, como gás hidrogênio, amônia, sulfetos e ferro ferroso. Os elétrons dessas moléculas entram na cadeia de transporte de elétrons, impulsionando a produção de ATP por meio da fosforilação oxidativa via ATP sintase. Os doadores inorgânicos liberam menos energia do que as moléculas orgânicas. Como resultado, menos prótons são bombeados através da membrana, resultando em menor produção de ATP. O oxigênio é o aceptor de elétrons mais comum, mas os quimiolitotróficos também podem usar nitrato, sulfato ou dióxido de carbono em condições anaeróbicas. A maioria dos quimiolitotróficos é autotrófica, usando sua energia para fixar dióxido de carbono e sintetizar moléculas orgânicas. Alguns deles dependem do fluxo reverso de elétrons para gerar energia redutora na forma de NADH. Isso ocorre quando o doador de elétrons tem um potencial redox maior do que o NAD+. Nesses casos, a energia da força motriz do próton é usada para empurrar os elétrons contra o gradiente para reduzir o NAD + a NADH.

vias de conservação de energia

Metabolism of Chemolithotrophs

Os quimiolitotr&#243;ficos s&#227;o microrganismos que obt&#234;m energia por meio da oxida&#231;&#227;o de mol&#233;culas inorg&#226;nicas, como g&#225;s hidrog&#234;nio (H_2), am&#244;nia (NH_3), compostos de enxofre reduzido (H_2S, S^2-) e ferro ferroso (Fe^2+). Diferentemente dos organismos heterotr&#243;ficos que dependem do carbono org&#226;nico, os quimiolitotr&#243;ficos transferem el&#233;trons desses doadores inorg&#226;nicos para a cadeia transportadora de el&#233;trons (ETC), gerando uma for&#231;a motriz de pr&#243;tons (PMF) que impulsiona a s&#237;ntese de ATP por fosforila&#231;&#227;o oxidativa. No entanto, como os doadores de el&#233;trons inorg&#226;nicos geralmente fornecem menos energia do que as mol&#233;culas org&#226;nicas, os quimiolitotr&#243;ficos precisam oxidar grandes quantidades de material inorg&#226;nico para sustentar seu crescimento.
A efici&#234;ncia da produ&#231;&#227;o de energia nos quimiolitotr&#243;ficos depende do potencial redox de seus doadores e aceptores de el&#233;trons. O oxig&#234;nio (O_2) &#233; o aceptor final de el&#233;trons mais comumente utilizado, pois possui um potencial redox altamente positivo, maximizando o rendimento energ&#233;tico. No entanto, alguns quimiolitotr&#243;ficos podem utilizar aceptores alternativos, como nitrato (NO_3^-), sulfato (SO_4^2-) ou di&#243;xido de carbono (CO_2) em condi&#231;&#245;es anaer&#243;bicas. Como as mol&#233;culas inorg&#226;nicas fornecem menos energia do que os substratos org&#226;nicos, as cadeias de transporte de el&#233;trons nos quimiolitotr&#243;ficos geralmente bombeiam menos pr&#243;tons atrav&#233;s da membrana, resultando em rendimentos de ATP inferiores aos dos organismos heterotr&#243;ficos.
A maioria dos quimiolitotr&#243;ficos &#233; autotr&#243;fica, ou seja, utiliza ATP e poder redutor para fixar CO_2 e sintetizar mol&#233;culas org&#226;nicas para crescimento. No entanto, alguns doadores de el&#233;trons inorg&#226;nicos, como Fe^2+ e NO_2^-, possuem potenciais redox mais elevados do que o par NAD^+/NADH, tornando termodinamicamente desfavor&#225;vel a redu&#231;&#227;o direta de NAD^+ a NADH. Para superar essa limita&#231;&#227;o, muitos quimiolitotr&#243;ficos utilizam o fluxo reverso de el&#233;trons, um processo que consome energia para for&#231;ar os el&#233;trons contra o gradiente termodin&#226;mico, a fim de produzir NADH para rea&#231;&#245;es biossint&#233;ticas.
Os quimiolitotr&#243;ficos s&#227;o classificados com base em seus doadores de el&#233;trons preferenciais. As bact&#233;rias oxidantes de hidrog&#234;nio utilizam H_2 como fonte de energia e transferem el&#233;trons para o NAD^+ ou para a ETC por meio de enzimas hidrogenases. As bact&#233;rias nitrificantes desempenham um papel crucial no ciclo do nitrog&#234;nio ao oxidar am&#244;nia (NH_3) a nitrito (NO_2^-) e, em seguida, a nitrato (NO_3^-), em um processo conhecido como nitrifica&#231;&#227;o. As bact&#233;rias oxidantes de enxofre metabolizam compostos de enxofre, como H_2S e S^2-, gerando sulfato (SO_4^2-) e ATP por fosforila&#231;&#227;o oxidativa e fosforila&#231;&#227;o em n&#237;vel de substrato. Adicionalmente, as bact&#233;rias anammox realizam a oxida&#231;&#227;o anaer&#243;bica da am&#244;nia, um processo singular que converte NH_4^+ e NO_2^- em g&#225;s nitrog&#234;nio (N_2), contribuindo para a perda de nitrog&#234;nio em ambientes aqu&#225;ticos.
Os quimiolitotr&#243;ficos desempenham um papel fundamental nos ciclos biogeoqu&#237;micos globais, particularmente nos ciclos do nitrog&#234;nio, enxofre e ferro. Eles contribuem para a transforma&#231;&#227;o e reciclagem de nutrientes essenciais nos ecossistemas, influenciando a qu&#237;mica do solo e da &#225;gua. Al&#233;m disso, esses microrganismos s&#227;o utilizados em diversas aplica&#231;&#245;es industriais e ambientais, como biorremedia&#231;&#227;o, biolixivia&#231;&#227;o e tratamento de &#225;guas residuais. Sua capacidade de prosperar em ambientes extremos, incluindo fontes hidrotermais em &#225;guas profundas e &#225;reas de drenagem &#225;cida de minas, destaca sua versatilidade metab&#243;lica e import&#226;ncia ecol&#243;gica.

Vias de conservação de energia

Os quimiolitotr&#243;ficos s&#227;o microrganismos que obt&#234;m energia por meio da oxida&#231;&#227;o de mol&#233;culas inorg&#226;nicas, como g&#225;s ...

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Microbial Metabolism

Metabolismo Microbiano

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how chemolithotrophs make atp

Chemolithotrophs make ATP by using inorganic chemicals as an energy source. They oxidize molecules such as hydrogen gas, ammonia, reduced sulfur compounds, and ferrous iron. Instead of relying on organic carbon like heterotrophs, they move electrons from these inorganic donors into the electron transport chain, or ETC.

That electron flow builds a proton motive force, or PMF. The PMF drives ATP synthesis through oxidative phosphorylation. Because inorganic electron donors usually release less energy than organic molecules, chemolithotrophs often need to oxidize large amounts of inorganic material to support growth.

Their energy yield depends on the redox potential of the electron donor and acceptor. Oxygen is the most common terminal electron acceptor because it has a highly positive redox potential and gives the best energy yield. Some chemolithotrophs can also use nitrate, sulfate, or carbon dioxide as acceptors when oxygen is not available.

These microbes usually make less ATP than heterotrophs because their ETCs often pump fewer protons across the membrane. Most chemolithotrophs are autotrophs, so they use ATP and reducing power to fix carbon dioxide and build organic molecules. Some donors, such as Fe2+ and NO2-, have a higher redox potential than the NAD+/NADH pair, so direct NADH formation is not favorable.

To solve this problem, many chemolithotrophs use reverse electron flow. This process spends energy to push electrons against the normal gradient and make NADH for biosynthesis. Hydrogen-oxidizing bacteria use H2 and transfer electrons with hydrogenase enzymes. Nitrifying bacteria oxidize ammonia to nitrite and then nitrate, which is called nitrification and is important in the nitrogen cycle.

Sulfur-oxidizing bacteria use compounds such as H2S and S2- and produce sulfate. They can make ATP through both oxidative phosphorylation and substrate-level phosphorylation. Anammox bacteria carry out anaerobic ammonia oxidation and convert NH4+ and NO2- into nitrogen gas, which contributes to nitrogen loss in aquatic environments.

Chemolithotrophs are key parts of the nitrogen, sulfur, and iron cycles. They help recycle nutrients and shape soil and water chemistry. They are also used in bioremediation, bioleaching, and wastewater treatment, and many can live in extreme places such as deep-sea hydrothermal vents and acidic mine drainage sites.

How Chemolithotrophs Make ATP

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atp and energy production

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Metabolism is the set of chemical reactions that keep living cells working. It includes reactions that break down biomolecules and reactions that build them up. These two sides of metabolism work together to support energy balance and cell function. Catabolic pathways break large molecules into smaller parts. Carbohydrates, lipids, and proteins can be broken down into monosaccharides, fatty acids, and amino acids. These reactions release energy, and cells store much of that energy as ATP, or...

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glycolysis

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other glycolytic pathways

Pentose Phosphate Pathway and Entner-Doudoroff

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cellular respiration

Cellular Respiration: ATP Production Pathways

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electron transport chain components

Electron Transport Chain and ATP Production

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Electron Transport Chain Powers ATP Output

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respiration pathways

TCA Cycle and Energy Pathways

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microbial fermentation

Fermentation Products in Microbes

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metabolism of chemolithotrophs

Chemolithotrophs make ATP by using inorganic chemicals as an energy source. They oxidize molecules such as hydrogen gas, ammonia, reduced sulfur compounds, and ferrous iron. Instead of relying on organic carbon like heterotrophs, they move electrons from these inorganic donors into the electron transport chain, or ETC. That electron flow builds a proton motive force, or PMF. The PMF drives ATP synthesis through oxidative phosphorylation. Because inorganic electron donors usually release less...

amino acid catabolism

Microbes Use Proteins for Energy

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lipid catabolism

How Microbes Break Down Fats for Energy

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oxygenic photosynthesis

How Plants Make Oxygen and ATP

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anoxygenic photosynthesis

Bacterial Light Capture Without Oxygen

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biosynthesis in bacteria

How Bacteria Build Key Macromolecules

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carbon-dioxide fixation

Microbial Carbon Fixation Pathways

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biosynthesis of polysaccharides

Activated Sugars for Polysaccharide Synthesis

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inorganic nitrogen assimilation

Nitrogen Uptake by Microbes

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sulfur assimilation

Sulfur Uptake and Cysteine Synthesis

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amino acid biosynthetic pathways

Amino Acid Building from Cell Metabolites

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biosynthesis of nucleic acids

Nucleotide Building Blocks for DNA and RNA

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biosynthesis of lipids

How Membrane Lipids Vary Across Life

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Lipopolysaccharides and Gram-Negative Defense

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key terms and concepts

Learn how chemolithotrophs use inorganic molecules like hydrogen, ammonia, sulfur, and iron to make ATP, fix CO2, and drive nitrogen and sulfur cycles.

How Chemolithotrophs Make ATP | 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

How Chemolithotrophs Make ATP

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