The current conditions of the Martian surface are considered prohibitive for life as we know it, due to strong radiation, highly oxidizing conditions, and relatively low water activity. Earth hosts a multitude of extreme environments whose physico-chemical properties partly match those currently existing on Mars or occurred over the geological time on the Red Planet. One of such environments, the Makgadikgadi Basin of Botswana, hosts a series of salt lakes (pans or playa) that present geological and chemical characteristics that may offer critical insights for astrobiological studies. The aim of this work is to characterize the physical and chemical boundaries within which terrestrial life may exist and, by comparison, assess the habitability of Mars. For the first time, we aim to provide a complete geomicrobiological and mineralogical characterization of the Kudiakam and Ntwetwe Pans (part of the Makgadikgadi Basin) surface sediments, in order to correlate the microbial biodiversity with the geological conditions. In order to achieve this, we measured a number of chemical and physical parameters (pH, alkalinity, conductivity) directly in the field. These were coupled with mineralogical data from XRD and geochemical data from XRF analyses. The data set was transferred into heat maps that were then compared with metabarcoding data in order to highlight correlations existing between physical/mineralogical conditions and the relative abundance/diversity of microorganisms. The sediments were further investigated for the presence of microbial micromorphologies using a SEM in order to provide important baseline data for the taxonomy of extremophiles in hypersaline environments on Earth and on Mars. This study is of significant interest to astrobiology investigations, allowing to assess the effects of a hypersaline environment on the survival potential of microorganisms and to understand if hypothetical life-forms may exist or have existed on Mars.
Correlation between geological characteristics of surficial playa deposits and microbial diversity in the Makgadikgadi pans (Botswana): implications for the search for life on Mars
Franchi F.Supervision
;
2024-01-01
Abstract
The current conditions of the Martian surface are considered prohibitive for life as we know it, due to strong radiation, highly oxidizing conditions, and relatively low water activity. Earth hosts a multitude of extreme environments whose physico-chemical properties partly match those currently existing on Mars or occurred over the geological time on the Red Planet. One of such environments, the Makgadikgadi Basin of Botswana, hosts a series of salt lakes (pans or playa) that present geological and chemical characteristics that may offer critical insights for astrobiological studies. The aim of this work is to characterize the physical and chemical boundaries within which terrestrial life may exist and, by comparison, assess the habitability of Mars. For the first time, we aim to provide a complete geomicrobiological and mineralogical characterization of the Kudiakam and Ntwetwe Pans (part of the Makgadikgadi Basin) surface sediments, in order to correlate the microbial biodiversity with the geological conditions. In order to achieve this, we measured a number of chemical and physical parameters (pH, alkalinity, conductivity) directly in the field. These were coupled with mineralogical data from XRD and geochemical data from XRF analyses. The data set was transferred into heat maps that were then compared with metabarcoding data in order to highlight correlations existing between physical/mineralogical conditions and the relative abundance/diversity of microorganisms. The sediments were further investigated for the presence of microbial micromorphologies using a SEM in order to provide important baseline data for the taxonomy of extremophiles in hypersaline environments on Earth and on Mars. This study is of significant interest to astrobiology investigations, allowing to assess the effects of a hypersaline environment on the survival potential of microorganisms and to understand if hypothetical life-forms may exist or have existed on Mars.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
