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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Survival of Extremophilic Yeasts in the Stratospheric Environment during Balloon Flights and in Laboratory Simulations

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Pulschen, Andre Arashiro [1] ; de Araujo, Gabriel Guarany [2] ; Souza Ramosde Carvalho, Ana Carolina [2] ; Cerini, Maria Fernanda [3, 4] ; Fonseca, Lucas de Mendonca [5] ; Galante, Douglas [3, 4] ; Rodrigues, Fabio [6]
Total Authors: 7
[1] Univ Sao Paulo, Inst Chem, Sao Paulo - Brazil
[2] Univ Sao Paulo, Interun Grad Program Biotechnol, Sao Paulo - Brazil
[3] Brazilian Ctr Res Energy & Mat, Brazilian Synchrotron Light Lab, Campinas, SP - Brazil
[4] Univ Sao Paulo, Sao Carlos Inst Phys, Grad Program Biomol Phys, Sao Paulo - Brazil
[5] Airvantis P&D Ltda, Sao Carlos, SP - Brazil
[6] Univ Sao Paulo, Inst Chem, Dept Fundamental Chem, Sao Paulo - Brazil
Total Affiliations: 6
Document type: Journal article
Source: Applied and Environmental Microbiology; v. 84, n. 23 DEC 2018.
Web of Science Citations: 3

The high-altitude atmosphere is a harsh environment with extremely low temperatures, low pressure, and high UV irradiation. For this reason, it has been proposed as an analogue for Mars, presenting deleterious factors similar to those on the surface of that planet. We evaluated the survival of extremophilic UV-resistant yeasts isolated from a high-elevation area in the Atacama Desert under stratospheric conditions. As biological controls, intrinsically resistant Bacillus subtilis spores were used. Experiments were performed in two independent stratospheric balloon flights and with an environmental simulation chamber. The three following different conditions were evaluated: (i) desiccation, (ii) desiccation plus exposure to stratospheric low pressure and temperature, and (3) desiccation plus exposure to the full stratospheric environment (UV, low pressure, and temperature). Two strains, Naganishia (Cryptococcus) friedmannii 16LV2 and Exophiala sp. strain 15LV1, survived full exposures to the stratosphere in larger numbers than did B. subtilis spores. Holtermanniella watticus (also known as Holtermanniella wattica) 16LV1, however, suffered a substantial loss in viability upon desiccation and did not survive the stratospheric UV exposure. The remarkable resilience of N. friedmannii and Exophiala sp. 15LV1 under the extreme Mars-like conditions of the stratosphere confirms its potential as a eukaryotic model for astrobiology. Additionally, our results with N. friedmannii strengthen the recent hypothesis that yeasts belonging to the Naganishia genus are fit for aerial dispersion, which might account for the observed abundance of this species in high-elevation soils. IMPORTANCE Studies of eukaryotic microorganisms under conditions of astrobiological relevance, as well as the aerial dispersion potential of extremophilic yeasts, are still lacking in the literature compared to works with bacteria. Using stratospheric balloon flights and a simulation chamber, we demonstrate that yeasts isolated from an extreme environment are capable of surviving all stressors found in the stratosphere, including intense UV irradiation, scoring an even higher survival than B. subtilis spores. Notably, the yeast N. friedmannii, which displayed one of the highest tolerances to the stratospheric environment in the experiments, was recently proposed to be adapted to airborne transportation, although such a hypothesis had not yet been tested. Our results strengthen such an assumption and can help explain the observed distribution and ecology of this particular yeast species. (AU)

FAPESP's process: 16/15054-7 - Environmental simulations and in situ spectroscopic characterization of potential molecular biosignatures with applications in space missions
Grantee:Maria Fernanda Cerini
Support Opportunities: Scholarships in Brazil - Master
FAPESP's process: 09/06012-5 - Multiparametric simulation of extraterrestrial environments
Grantee:Douglas Galante
Support Opportunities: Scholarships in Brazil - Post-Doctoral