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

Il mare profondo, a profondità superiori a 1.000 metri, è caratterizzato da temperature fredde di 2–3 gradi Celsius, un'immensa pressione idrostatica che aumenta di circa 1 atmosfera ogni 10 metri e bassi livelli di nutrienti.I microbi piezotolleranti sono quelli che possono tollerare condizioni di alta pressione e rimanere vitali sotto di esse, come i membri del genere Colwellia.D'altra parte, veri piezofili, come le specie di Moritella , crescono e sopravvivono meglio sotto alta pressione grazie a meccanismi cellulari specifici.Ad esempio, per mantenere la fluidità delle membrane e la stabilità delle proteine ad alta pressione, i piezofili aumentano la proporzione di acidi grassi insaturi nelle loro membrane. Alcune specie esprimono proteine regolate dalla pressione come l'OmpH attraverso sistemi di trascrizione sensibili alla pressione.Sotto i 2.000 metri, i sedimenti ospitano riduttori di solfato e organismi ossidanti del metano, insieme ad altri microbi adattati a limitazioni energetiche estreme.Questa scarsità porta a densità cellulari molto più basse rispetto alle regioni più basse.

ecologia microbica delle profondità marine

Deep Sea Microbial Ecology

L'oceano profondo e i suoi sedimenti sottostanti rappresentano vasti habitat microbici in gran parte inesplorati che si estendono ben oltre la zona fotica illuminata dal sole. La zona fotica (eufotica) si estende tipicamente per i ~100–200 metri superiori delle acque pelagiche in mare aperto, ma la sua profondità varia geograficamente e stagionalmente, dove sufficiente luce supporta la vita fotosintetica. Sotto questo si trova il mare profondo, che si estende per circa 1000–6000 metri (zone batippelagiche ad abissali), con trincee hadali più profonde che superano i 6000 metri. Questa regione è caratterizzata da oscurità totale, temperature gelide (2–3°C, che possono essere leggermente più alte nelle bocche idrotermali), alta pressione idrostatica che aumenta dalla superficie di ~1 atm ogni 10 m (ad esempio, ~100 atm a 1000 m) e gravi limitazioni di nutrienti.I microrganismi che abitano queste profondità mostrano adattamenti fisiologici unici. Alcuni, come i microbi piezotolleranti, tollerano alte pressioni ma crescono in modo ottimale a 1 atmosfera. Altri, chiamati piezofili, crescono meglio sotto alta pressione, tipicamente intorno a 300–400 atmosfere, e piezofili estremi come Moritella spp. della Fossa delle Marianne richiedono pressioni superiori a 700 atmosfere per crescere. Per adattarsi, questi organismi sviluppano diversi processi cellulari unici, come l'aumento degli acidi grassi insaturi per mantenere la fluidità della membrana sotto pressione, ed esprimere proteine sensibili alla pressione come l'OmpH.Sotto il fondale marino, la vita microbica continua nei sedimenti delle profondità marine, formando una delle più grandi biosfere microbiche della Terra. La densità microbica dei sedimenti diminuisce con la profondità, passando da circa 10⁹ cellule/g in superficie a meno di 10³ cellule/g a centinaia di metri di profondità. Questa diminuzione corrisponde a una riduzione della disponibilità energetica dovuta all'esaurimento della materia organica e degli accettori terminali di elettroni come il solfato. Nei margini continentali ricchi di nutrienti, il solfato viene consumato rapidamente, dando il via alla metanogenesi. D'altra parte, nei sedimenti oceanici profondi poveri di organici, il solfato può persistere fino al basamento basaltico.Nonostante le basse densità cellulari, il volume di sedimenti ospita circa 5,4 × 10²⁹ cellule procariotiche. Il metabolismo microbico in queste zone si basa su materia organica lentamente degradabile e composti prodotti geochimicamente come metano, idrogeno e acetato. Gli studi filogenetici rivelano una predominanza di Archea non coltivate, inclusi i Bathyarchaeota e le Proteobatteri riducenti di solfato, tutti adattati a estremi limiti energetici attraverso una crescita lenta, genomi compatti e vie anaerobiche specializzate.

Ecologia microbica delle profondità marine

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

Didattica

JoVE Core

Microbiology

Microbiologia

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Unità

Microbial Ecology

Ecologia microbica

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

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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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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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

Deep Sea Microbes and Extreme Conditions

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