Strange life forms hidden in ancient Hawaiian lava caves

American scientists have managed to identify a great diversity of unique microbial species, which have developed in geothermal caves, lava tubes and volcanic fumaroles on the island of Hawaii. These underground structures formed between 65 and 800 years ago and receive little or no sunlight, in environments similar to those that can be found on Mars.

New research recently published in the journal Frontiers in Microbiology, and led by specialist Rebecca Prescott, from the University of Hawaii at Manoa, has revealed an enormous underground microbial community that grows in ancient lava caves in Hawaii, in conditions that would be impossible for other life forms to overcome.

Scientists know that microbes They are the smallest living organisms known on Earth and can be found in almost every corner of our planet, even in the cold conditions of the lava caves in Hawaii, where sunlight practically does not reach. These environments are similar to those that can be found in formations of mars: Therefore, they could reveal important characteristics when searching for some type of extraterrestrial life.

The “dark matter” of the Earth’s subsurface

According to an article published in Science Alert, microbes represent the majority of the biomass on our planet after plants, and make up almost all of the biomass in the world. deep subsurface of the Earth. But since these organisms are so small and live in such extreme environments, science has not studied them throughout history as the importance of their impact on terrestrial environments really deserves.

Although in recent years this situation has begun to change, recent estimates indicate that 99.9% of all microbe species they remain unknown. Consequently, some researchers have dubbed this gigantic undiscovered microbial community a kind of “dark matter” hidden on our own planet.

In Hawaii, the underground structures studied formed approximately 65 to 800 years ago: in addition to microbial mats, which are a common feature of these lava caves, they can also harbor minerals and toxic gases. However, both these conditions and the minimal contribution of sunlight have not prevented the development of unique life forms: Samples collected between 2006 and 2019 do not show any genetic coincidence with previously known genera or species.

The manifestations of these strange forms of life show differences depending on the context. In the oldest caves, formed between 500 and 800 years ago, microbial populations were more diverse than in geothermally active sites or structures less than 400 years old. Despite this, the youngest and most active sites presented more complex microbial interactions and a greater tendency towards community life.

Adaptability

Researchers believe it takes time for microbes to master underground spaces, but just as the environment around them changes over time, so do they. modify the structure of their community. For example, in the caves where the lowest temperatures are recorded, it was found that proteobacteria and actinobacteria are more frequent.

On the other hand, some types of bacteria such as Chloroflexi and Acidobacteria They proliferated in almost all spaces, beyond the age of the underground formations. Apparently, these microbes seem to be leading actors in communities of microorganisms, taking the role of central species destined to congregate other microbes.

Another crucial aspect that scientists managed to discover is that microbes of the Chloroflexi species can probably provide carbon sources in these extreme ecosystems, by harnessing the energy of sunlight even in conditions of relative darkness. The results of the research highlight the need to continue delving into the study of these microbial communities in natural environments, because they apparently have a lot to say about the origin of life on Earth and on other planets in the Solar System.

Reference

Islands Within Islands: Bacterial Phylogenetic Structure and Consortia in Hawaiian Lava Caves and Fumaroles. Rebecca D. Prescott et al. Frontiers in Microbiology (2022). DOI:https://doi.org/10.3389/fmicb.2022.934708

(An earlier version of this article was published on July 25, 2022).

2024-06-23 06:40:49
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