Name: deep sea microbes and extreme conditions
Uploaded: 2026-03-12T13:57:45.000Z
Duration: 1 min 18 s
Channel: JoVE

O mar profundo, em profundidades superiores a 1.000 metros, é marcado por temperaturas frias de 2–3 graus Celsius, imensa pressão hidrostática que aumenta aproximadamente 1 atmosfera a cada 10 metros e baixos níveis de nutrientes.Microrganismos piezotolerantes são aqueles que toleram condições de alta pressão e permanecem viáveis sob elas, como os membros do gênero Colwellia.Por outro lado, verdadeiros piezófilos, como espécies de Moritella , crescem e sobrevivem melhor sob alta pressão por meio de mecanismos celulares específicos.Por exemplo, para manter a fluidez das membranas e a estabilidade das proteínas sob alta pressão, os piezófilos aumentam a proporção de ácidos graxos insaturados em suas membranas. Algumas espécies expressam proteínas reguladas por pressão, como o OmpH, por meio de sistemas de transcrição sensíveis à pressão.Abaixo de 2.000 metros, os sedimentos abrigam redutores de sulfato e organismos oxidadores de metano, junto com outros microrganismos adaptados à limitação extrema de energia.Essa escassez resulta em densidades celulares muito menores do que em regiões mais rasas.

deep sea microbial ecology

Deep Sea Microbial Ecology

O oceano profundo e seus sedimentos subjacentes representam vastos habitats microbianos, em grande parte inexplorados, que se estendem muito al&#xE9;m da zona f&#xF3;tica iluminada pelo sol. A zona f&#xF3;tica, ou euf&#xF3;tica, tipicamente abrange os primeiros ~100&#x2013;200 m das &#xE1;guas pel&#xE1;gicas no oceano aberto, mas sua profundidade varia geogr&#xE1;fica e sazonalmente, onde a luz suficiente sustenta a vida fotossint&#xE9;tica. Abaixo desta encontra-se o oceano profundo, que se estende aproximadamente de 1.000 a 6.000 m, das zonas batipel&#xE1;gica &#xE0; abissal, com fossas hadais mais profundas que se estendem al&#xE9;m de 6.000 m. Essa regi&#xE3;o &#xE9; marcada por escurid&#xE3;o completa, temperaturas g&#xE9;lidas (2&#x2013;3&#xB0;C, que podem ser ligeiramente mais altas em fontes hidrotermais), alta press&#xE3;o hidrost&#xE1;tica que aumenta a partir da superf&#xED;cie em ~101,33 kPa por 10 m (por exemplo, ~10,13 MPa a 1.000 m) e severas limita&#xE7;&#xF5;es de nutrientes.
Os microrganismos que habitam essas profundezas apresentam adapta&#xE7;&#xF5;es fisiol&#xF3;gicas &#xFA;nicas. Alguns, como os microrganismos piezotolerantes, toleram altas press&#xF5;es, mas crescem de forma &#xF3;tima a 101,33 kPa. Outros, denominados piez&#xF3;filos, crescem melhor sob alta press&#xE3;o, tipicamente em torno de 30,40&#x2013;40,53 MPa, e piez&#xF3;filos extremos, como esp&#xE9;cies de Moritella da Fossa das Marianas, requerem press&#xF5;es acima de 70,93 MPa para crescer. Para se adaptarem, esses organismos desenvolvem diversos processos celulares &#xFA;nicos, como o aumento de &#xE1;cidos graxos insaturados para manter a fluidez da membrana sob press&#xE3;o e a express&#xE3;o de prote&#xED;nas sens&#xED;veis &#xE0; press&#xE3;o, como OmpH.
Abaixo do assoalho oce&#xE2;nico, a vida microbiana continua nos sedimentos marinhos profundos, formando uma das maiores biosferas microbianas da Terra. A densidade microbiana nos sedimentos diminui com a profundidade, de cerca de 10&#x2079; c&#xE9;lulas/g na superf&#xED;cie para menos de 10&#xB3; c&#xE9;lulas/g a centenas de metros de profundidade. Essa queda corresponde &#xE0; redu&#xE7;&#xE3;o da disponibilidade de energia devido ao esgotamento da mat&#xE9;ria org&#xE2;nica e de aceptores terminais de el&#xE9;trons, como o sulfato. Em margens continentais ricas em nutrientes, o sulfato &#xE9; consumido rapidamente, dando lugar &#xE0; metanog&#xEA;nese. Por outro lado, em sedimentos do oceano profundo pobres em mat&#xE9;ria org&#xE2;nica, o sulfato pode persistir at&#xE9; o embasamento bas&#xE1;ltico.
Apesar da baixa densidade celular, o enorme volume de sedimentos abriga cerca de 5.4 &#xD7; 10&#xB2;&#x2079; c&#xE9;lulas procari&#xF3;ticas. O metabolismo microbiano nessas zonas depende de mat&#xE9;ria org&#xE2;nica de degrada&#xE7;&#xE3;o lenta e de compostos produzidos geoquimicamente, como metano, hidrog&#xEA;nio e acetato. Estudos filogen&#xE9;ticos revelam o predom&#xED;nio de Archaea n&#xE3;o cultivadas, incluindo Bathyarchaeota, e de Proteobacteria redutoras de sulfato, todas adaptadas a limita&#xE7;&#xF5;es energ&#xE9;ticas extremas por meio de crescimento lento, genomas compactos e vias anaer&#xF3;bias especializadas.

The deep ocean and its underlying sediments represent vast, largely unexplored microbial habitats that extend far beyond the sunlit photic zone. The ...

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Education

JoVE Core

Microbiology

Microbiologia

Unit

Unidade

Microbial Ecology

Ecologia Microbiana

KEY TERMS AND CONCEPTS

TERMOS E CONCEITOS-CHAVE

deep sea microbes and extreme conditions

Deep sea microbes live in one of Earth’s harshest environments. The deep ocean is far below the sunlit photic zone, which usually reaches the upper 100 to 200 meters of open water. Below that layer, the bathypelagic and abyssal zones stretch from about 1,000 to 6,000 meters, and hadal trenches go even deeper.

This region is dark, cold, and highly pressurized. Temperatures are usually around 2 to 3°C, although hydrothermal vents can be slightly warmer. Pressure rises by about 1 atmosphere for every 10 meters of depth, so it reaches about 100 atmospheres at 1,000 meters. Nutrients are also scarce, which makes life difficult for microbes.

Some deep sea microorganisms are piezotolerant. This means they can handle high pressure but still grow best at 1 atmosphere. Others are piezophiles, which grow best under high pressure, often around 300 to 400 atmospheres. Extreme piezophiles, such as Moritella species from the Mariana Trench, need pressures above 700 atmospheres to grow.

These microbes survive through special cell changes. Many increase the amount of unsaturated fatty acids in their membranes so the membranes stay fluid under pressure. Some also express pressure-sensitive proteins such as OmpH. These adaptations help cells function in conditions that would damage most surface-dwelling life.

Life also continues beneath the seafloor in deep-sea sediments. This subsurface habitat is one of the largest microbial biospheres on Earth. Microbial density drops with depth, from about 10^9 cells per gram near the surface to fewer than 10^3 cells per gram at hundreds of meters down.

That decline reflects lower energy supply. Organic matter becomes depleted, and terminal electron acceptors such as sulfate are used up. On nutrient-rich continental margins, sulfate disappears quickly and methanogenesis begins. In organic-poor deep-ocean sediments, sulfate can remain all the way to the basaltic basement.

Even with very low cell numbers, the total sediment volume is enormous. It may contain an estimated 5.4 × 10^29 prokaryotic cells. These microbes use slowly degradable organic matter and compounds made geochemically, including methane, hydrogen, and acetate.

Many of the organisms found there are still uncultured. Phylogenetic studies often show Archaea, including Bathyarchaeota, and sulfate-reducing Proteobacteria. They are adapted to extreme energy limits through slow growth, compact genomes, and specialized anaerobic pathways.

Deep Sea Microbes and Extreme Conditions

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Deep sea microbes live in one of Earth’s harshest environments. The deep ocean is far below the sunlit photic zone, which usually reaches the upper 100 to 200 meters of open water. Below that layer, the bathypelagic and abyssal zones stretch from about 1,000 to 6,000 meters, and hadal trenches go even deeper. This region is dark, cold, and highly pressurized. Temperatures are usually around 2 to 3°C, although hydrothermal vents can be slightly warmer. Pressure rises by about 1 atmosphere for...

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key terms and concepts

Explore how deep sea microbes survive cold, dark, high-pressure waters and nutrient-poor sediments through special adaptations and slow metabolism.

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microbiology

Deep Sea Microbes and Extreme Conditions

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