Anaerobic microorganisms in astrobiological analogue environments: from field site to culture collection

Abstract

Astrobiology seeks to understand the limits of life and to determine the physiology of organisms in order to better assess the habitability of other worlds. To successfully achieve these goals we require microorganisms from environments on Earth that approximate to extraterrestrial environments in terms of physical and/or chemical conditions. The most challenging of these environments with respect to sample collection, isolation and cultivation of microorganisms are anoxic environments. In this paper, an approach to this challenge was implemented within the European Union's MASE (Mars Analogues for Space Exploration) project. In this review paper, we aim to provide a set of methods for future field work and sampling campaigns. A number of anoxic environment based on characteristics that make them analogous to past and present locations on Mars were selected. They included anoxic sulphur-rich springs (Germany), the salt-rich Boulby Mine (UK), a lake in a basaltic context (Iceland), acidic sediments in the Rio Tinto (Spain), glacier samples (Austria) and permafrost samples (Russia and Canada). Samples were collected under strict anoxic conditions to be used for cultivation and genomic community analysis. Using the samples, a culturing approach was implemented to enrich anaerobic organisms using a defined medium that would allow for organisms to be grown under identical conditions in future physiological comparisons. Anaerobic microorganisms were isolated and deposited with the DSMZ (Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH) culture collection to make them available to other scientists. In MASE, the selected organisms are studied with respect to survival and growth under Mars relevant stresses. They are artificially fossilized and the resulting biosignatures studied and used to investigate the efficacy of life detection instrumentation for planetary missions. Some of the organisms belong to genera with medical and environmental importance such as Yersinia spp., illustrating how astrobiology field research can be used to increase the availability of microbial isolates for applied terrestrial purposes.

Stress-Tolerance and Taxonomy of Culturable Bacterial Communities Isolated from a Central Mojave Desert Soil Sample

“…Stress effects, such as low water availability, nutrients deficiencies, high levels of solar radiation, and wide temperature fluctuations in the surface soil of the Mojave Desert lead to the formation of physiological survival strategies for prokaryotes existing under these conditions [2,3]. Our study revealed a high diversity (both taxonomic and morphophysiological) of culturable bacteria in the investigated soil.…”

“…One of the main tasks of modern astrobiology is studying environmental factors of different space bodies and outer space and to determine surviving and functioning limits of terrestrial life forms under extraterrestrial conditions [1,2].…”

Survivability of Soil and Permafrost Microbial Communities after Irradiation with Accelerated Electrons under Simulated Martian and Open Space Conditions

“…Inside the chamber there is a thermocouple (5) for temperature control. The chamber together with the liquid nitrogen tank is thermally insulated with a syntepon bounded by an isilone cylinder (1). The chamber can maintain a pressure of ~0.01 Torr and a temperature of about −130 °C.…”

“…TPC-The samples, exposed to the low pressure and low temperature without irradiation. 1 The strain was isolated earlier in the course of other studies, see Section 2.1.…”

“…Despite the long-standing scientific interest in the problem of living cell resistance to adverse impacts, and numerous biological studies of extreme habitats, the question of the limits of cell viability in native environment under stress conditions remains open, and in recent decades has acquired the scale of an astrobiological problem. The viability of microorganisms under the influence of extraterrestrial cosmic factors is one of the priority issues of modern astrobiological studies [1][2][3]. Much attention is paid to ionizing radiation being considered as one of the main factors that can prevent the preservation and spread of life outside the Earth [4][5][6][7][8][9][10].…”