Ultra-small microorganisms in the polyextreme conditions of the Dallol volcano, Northern Afar, Ethiopia

Abstract

The Dallol geothermal area in the northern part of the Danakil Depression (up to 124–155 meter below sea level) is deemed one of the most extreme environments on Earth. The area is notable for being part of the Afar Depression, an incipient seafloor-spreading center located at the triple junction, between Nubian, Somali and Arabian plates, and for hosting environments at the very edge of natural physical-chemical extremities. The northern part of the Danakil Depression is dominated by the Assale salt plain (an accumulation of marine evaporite deposits) and hosts the Dallol volcano. Here, the interaction between the evaporitic deposit and the volcanisms have created the unique Dallol hot springs, which are highly acidic (pH ~ 0) and saline (saturation) with maximum temperatures ranging between 90 and 109 °C. Here we report for the first time evidence of life existing with these hot springs using a combination of morphological and molecular analyses. Ultra-small structures are shown to be entombed within mineral deposits, which are identified as members of the Order Nanohaloarchaea. The results from this study suggest the microorganisms can survive, and potential live, within this extreme environment, which has implications for understanding the limits of habitability on Earth and on (early) Mars.

The Venusian Lower Atmosphere Haze as a Depot for Desiccated Microbial Life: A Proposed Life Cycle for Persistence of the Venusian Aerial Biosphere

“…Preliminary studies suggest that even in such harsh polyextreme hydrothermal conditions, life can survive and possibly even thrive; there are examples suggesting that the Dallol acidic pools are inhabited by very small (*0.2 mm cell size) Nanohaloarchaea and other phyla of archaea (Belilla et al, 2019;Gómez et al, 2019). (Note that there is one Dallol pool where life has not yet been detected; instead of NaCl, the salts are composed of Mg 2+ and Ca 2+ ions.)…”

Ecological and Biotechnological Aspects of Pigmented Microbes: A Way Forward in Development of Food and Pharmaceutical Grade Pigments

“…In contrast to microbial pigments, mineral pigments are intensely colored inorganic molecules with potential applications in artistic, cosmetic, forensic, archaeological, and evolutionary perspectives [ 55 ]. In the evolutionary perspective and according to the clay-mineral theory on the chemical origin of life [ 128 ] and recent evidences [ 129 ], we may be able to interlink the origin of molecules, including pigments in protocell, which helped protocells to survive in extreme conditions and supported the formation of multicellular organisms.…”

“…Since protocells’ origin, natural pigments have transformed into various phenomena such as pigments, fluorescence, and bioluminescence, found in prokaryotes and eukaryotes. Currently, researchers believe that life had originated 4.5 billion years ago from the extreme environment like hydrothermal vents in the ocean [ 130 ] or warm water pools in the volcanic land or geothermal (hot spring) areas [ 129 , 131 , 132 ], based on the evidences of hypothetic protocell structures, i.e., vesicles formed by simple fatty acids [ 130 ] and proteins [ 133 ], RNA [ 131 ] and DNA molecules [ 129 ]. The abundant external red pigments seen in deep-sea tubeworms at hydrothermal vents are indeed hemoglobins that act as binding sites to oxygen and hydrogen sulfide and transport these molecules to internal bacterial symbionts [ 134 ].…”

Producir más alimentos de forma sostenible es posible

“…However, some less common species may be essential in the adaption of plants to extreme conditions. Microorganisms have recently been identified in the Danakil Depression (Ethiopia), one of the most inhospitable environments on the planet, whose soil is thought to be akin to that of Mars (Gómez et al, 2019). Indeed, if these identified microorganisms favour plant growth, they could be used to develop «extraplanetary agriculture».…”