Enceladus as a Potential Niche for Methanogens and Estimation of Its Biomass.

Laura I Tenelanda-Osorio,Pablo Cuartas-Restrepo,Jorge I Zuluaga,Juan L Parra

doi:10.3390/life11111182

Laura I Tenelanda-Osorio, Pablo Cuartas-Restrepo + Show 2 more

Open Access

https://doi.org/10.3390/life11111182

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Journal: Life	Publication Date: Nov 5, 2021
Citations: 6	License type: CC BY 4.0

Affiliation: University of Antioquia

Abstract

Enceladus is a potential target for future astrobiological missions. NASA’s Cassini spacecraft demonstrated that the Saturnian moon harbors a salty ocean beneath its icy crust and the existence and analysis of the plume suggest water–rock reactions, consistent with the possible presence of hydrothermal vents. Particularly, the plume analysis revealed the presence of molecular hydrogen, which may be used as an energy source by microorganisms ( e.g., methanogens). This could support the possibility that populations of methanogens could establish in such environments if they exist on Enceladus. We took a macroscale approximation using ecological niche modeling to evaluate whether conditions suitable for methanogenic archaea on Earth are expected in Enceladus. In addition, we employed a new approach for computing the biomass using the Monod growth model. The response curves for the environmental variables performed well statistically, indicating that simple correlative models may be used to approximate large-scale distributions of these genera on Earth. We found that the potential hydrothermal conditions on Enceladus fit within the macroscale conditions identified as suitable for methanogens on Earth, and estimated a concentration of – cells/cm.

Highlights

In recent years, Saturn’s moon Enceladus has gained the attention of astrobiologists due to the presence of a big ocean of salty water beneath an icy crust, the internal sources of energy, and the presence of macromolecules identified in the plume, which supports the habitability potential of the moon
Based on the availability of H2 for metabolic conversion, we report the potential biomass of methanogenic archaea from a new approach, using the Monod growth model, which is an empirical model for calculating the growth of microorganisms mainly on aqueous environments [51]
Predictions from all niche models were statistically different from the null model and statistically appropriate to describe the fundamental niche at a coarse scale

Summary

Introduction

Saturn’s moon Enceladus has gained the attention of astrobiologists due to the presence of a big ocean of salty water beneath an icy crust, the internal sources of energy, and the presence of macromolecules (such as hydrocarbons) identified in the plume, which supports the habitability potential of the moon. Hydrothermal vents (on Earth) are unique sites with a wide variety of extreme environments that are important as they give an insight into the processes connected to the origin of life on Earth [8,9,10,11,12]. These structures form in the benthic zone of the ocean, in the vicinity of volcanoes, where water interacts with magma through the tectonic plates, and after cooling down, the dissolved minerals solidify, forming the structures known as hydrothermal vents [13]. Prokaryotes isolated from these environments are mostly hyperthermophilic microorganisms belonging to the domain Archaea [16,17]

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