Microbial Life in the Mariana Trench

The Mariana Trench, a remote and mysterious deep-sea trench in the western North Pacific Ocean, represents some of the most extreme depths and uncharted areas of Earth's oceans. 1

Plummeting to depths surpassing 36,000 feet (11,000 metres), it represents the deepest chasm known to humanity, a realm shrouded in perpetual darkness and subject to unfathomable pressures. 1

In this seemingly inhospitable environment, where even sunlight cannot penetrate, the weight of the ocean above exerts pressures exceeding 1,000 times that of the surface. Here lies a thriving ecosystem that defies the conventional understanding that underlies our existence on land - microbial life has found a way to flourish.2

Image Credit: DOERS/Shutterstock.comImage Credit: DOERS/Shutterstock.com

Microbial Diversity and Adaptations

Microbial diversity within the Mariana Trench is a testament to the adaptability and resilience of life under extreme conditions, whereby within the dark recesses of the trench, a myriad of microorganisms have evolved specialised adaptations to cope with the relentless pressures and frigid temperatures that characterise this abyssal domain.

Among them are piezophiles, microorganisms uniquely adapted to thrive under high pressure, their cellular structures reinforced to withstand the crushing weight of the ocean depths.3

Psychrophiles, in turn, have adapted to the icy cold, their metabolic processes finely tuned to operate in near-freezing temperatures.4

Barophiles, adept at thriving in high-pressure environments, have evolved mechanisms to maintain cellular integrity and function amidst the extreme forces exerted by the surrounding ocean.5

Other microbial life forms include alkaliphiles and thermophiles, and as their names suggest, alkali-liking and heat-liking, respectively, as well as actinomycetes, fungi, and non-extremophilic bacteria.4

Role of Microorganisms in Deep-Sea Ecosystems

The role of microorganisms in sustaining deep-sea ecosystems cannot be overstated. Within the lightless confines of the Mariana Trench, where photosynthesis is impossible, microbial communities rely on alternative energy sources to fuel their existence.

Chemosynthetic microorganisms, utilising the chemical energy derived from inorganic compounds such as hydrogen sulphide and methane, form the foundation of the trench's food web.6

These microbial communities produce organic matter through chemosynthesis, serving as the primary energy source for diverse deep-sea organisms.7

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Potential Biotechnological Applications

Teeming with life, the Mariana Trench is also a place that harbours much potential for biotechnological innovation. One promising avenue involves harnessing hydrolases found within this unique environment. 8

Such enzymes, sourced from marine, anaerobic, and extremophilic bacteria, hold promise for various biotechnological applications.8

Extremophile characteristics are particularly valuable for generating recombinants with specific attributes, whereas psychrophile enzymes, for instance, offer advantages like lower energy requirements. 8

By leveraging these features, psychrophiles could play a crucial role in genetic engineering to produce thermolabile proteins.8

Furthermore, another intriguing area involves stabilising hydrolytic enzymes, which show potential applications in chemistry, pharmaceuticals, and medicine. 8

Achieving enzyme stabilisation typically involves employing advanced techniques from chemical or protein engineering to enhance their resilience and effectiveness for practical use. 8

Two approaches to protein engineering have emerged during the last 20 years as effective ways to modify or enhance enzyme catalysis: the first is directed evolution, this is where random mutagenesis is conducted on a protein; the second method is through rational protein design, which is performed to modify the properties of a protein and is accomplished by understanding its structure as well as function to which these methods have shown to be successful in increasing activity, selectivity, or thermostability of proteins. 8

Approximately 150 industrial processes benefit from the usage of enzymes or catalysts derived from microorganisms, and currently more than 500 goods are created employing them. 8

In addition, approximately 65% of hydrolases are employed in the detergent, textile, pulp, paper, and starch industries, whereby around 25% of those enzymes are used in food processing overall, proving to be a promising and beneficial procedure.

Research indicates that there may be more diversity among extremophile microorganisms than previously believed. However, the challenge of isolating and cultivating these microorganisms makes the characterisation and application of such a diversity of enzymes problematic. 8

Future Research Directions

Regarding the future directions for microbial life in the Mariana Trench, unprecedented advancements in our knowledge of microbial life in the hadal zone have been made possible by the advent of sampling strategies and culture-independent approaches for microbial investigation. 9

Nonetheless, several significant problems still need to be addressed. For example, it is not entirely understood how high hydrostatic pressure affects the vertical distribution of microorganisms, even though it is thought to alter the variety and metabolism of bacterioplankton. 9

It is also unknown how microorganisms use complex carbohydrates and how they continue to function in the face of high hydrostatic pressure. 9

Thus, further research into the hydrolase process and ecological significance of microbial biofilm formation is essential in understanding the diversity of life within the Mariana Trench.


  1. The Editors of Encyclopedia Britannica. Mariana Trench | Facts, Maps, & Pictures. In: Encyclopædia Britannica [Internet]. 2018. Available from: https://www.britannica.com/place/Mariana-Trench
  2. Leeds U of. How fish survive extreme pressures of ocean life [Internet]. www.leeds.ac.uk. 2022. Available from: https://www.leeds.ac.uk/news-science/news/article/5155/how-fish-survive-extreme-pressures-of-ocean-life
  3. Liu P, Ding W, Lai Q, Liu R, Wei Y, Wang L, et al. Physiological and genomic features of Paraoceanicella profunda gen. nov., sp. nov., a novel piezophile isolated from deep seawater of the Mariana Trench. MicrobiologyOpen. 2019 Nov 19;9(2).
  4. Takami H, Inoue A, Fuji F, Horikoshi K. Microbial flora in the deepest sea mud of the Mariana Trench. FEMS Microbiology Letters. 2006 Jan 17;152(2):279–85.
  5. Kato C, Li L, Nogi Y, Nakamura Y, Tamaoka J, Horikoshi K. Extremely Barophilic Bacteria Isolated from the Mariana Trench, Challenger Deep, at a Depth of 11,000 Meters. Applied and Environmental Microbiology [Internet]. 1998 Apr 1;64(4):1510–3. Available from: https://aem.asm.org/content/64/4/1510
  6. Methane Support Systems of Deep Sea Ecosystems [Internet]. Schmidt Ocean Institute. 2018 [cited 2024 Mar 13]. Available from: https://schmidtocean.org/cruise-log-post/methane-support-systems-of-deep-sea-ecosystems/
  7. NatGeoUK. Possible microbes in the Mariana Trench hint at life on Jupiter’s moon [Internet]. National Geographic. 2020 [cited 2024 Mar 13]. Available from: https://www.nationalgeographic.co.uk/science-and-technology/2020/05/possible-microbes-in-the-mariana-trench-hint-at-life-on-jupiters-moon
  8. Dalmaso G, Ferreira D, Vermelho A. Marine Extremophiles: A Source of Hydrolases for Biotechnological Applications. Marine Drugs. 2015 Apr 3;13(4):1925–65.
  9. Fan S, Wang M, Ding W, Li YX, Zhang Y, Zhang W. Scientific and technological progress in the microbial exploration of the hadal zone. Marine Life Science & Technology. 2021 Aug 10;4(1):127–37

Further Reading 

Last Updated: Jul 3, 2024

Chi Cheng

Written by

Chi Cheng

Having graduated in Pharmacology BSc (Hons), followed by the completion of a Master of Science in Biomedical and Molecular Sciences, Chi’s interests spans widely across many areas of scientific enquiry within the life sciences and beyond. This has been demonstrated with his successful completion of modules relating to pharmacology, neuroscience, organic chemistry, biomedical science, as well as animal and plant biology, during his academic pursuits.


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