Abstract
The black fungi Cryomyces antarcticus and Cryomyces minteri are highly melanized and are resilient to cold, ultra-violet, ionizing radiation and other extreme conditions. These microorganisms were isolated from cryptoendolithic microbial communities in the McMurdo Dry Valleys (Antarctica) and studied in Low Earth Orbit (LEO), using the EXPOSE-E facility on the International Space Station (ISS). Previously, it was demonstrated that C. antarcticus and C. minteri survive the hostile conditions of space (vacuum, temperature fluctuations, and the full spectrum of extraterrestrial solar electromagnetic radiation), as well as Mars conditions that were simulated in space for a 1.5-year period. Here, we qualitatively and quantitatively characterize damage to DNA and cellular ultrastructure in desiccated cells of these two species, within the frame of the same experiment. The DNA and cells of C. antarcticus exhibited a higher resistance than those of C. minteri. This is presumably attributable to the thicker (melanized) cell wall of the former. Generally, DNA was readily detected (by PCR) regardless of exposure conditions or fungal species, but the C. minteri DNA had been more-extensively mutated. We discuss the implications for using DNA, when properly shielded, as a biosignature of recently extinct or extant life.
Highlights
Microorganisms able to tolerate or thrive in habitats which are lethal or detrimental for most terrestrial life-forms are defined as extremophiles
The possible existence of life on other planets and the capacity to survive space irradiation, The possible existence of life on other to planets and the capacity to an survive space irradiation, potentially allowing some microorganisms pass unimpeded through interplanetary transfer potentially allowing some microorganisms to pass unimpeded through an interplanetary transfer and and disseminate throughout the universe, is one of the main questions in Astrobiology
C. minteri CCFEE 5187 were tested in ground-based experiments, and in space
Summary
Microorganisms able to tolerate or thrive in habitats which are lethal or detrimental for most terrestrial life-forms are defined as extremophiles. The two black fungi Cryomyces antarcticus and Cryomyces minteri are cryptoendolithic and microBIOPAN exposure facility on the FOTON capsule, where lichens survived a two-week exposure to colonial species that occur within sandstone outcrops of the McMurdo Dry Valleys of Antarctica the Low Earth Orbit (LEO) environment [8]; lichens and cyanobacteria survived a 10-day exposure (Southern Victoria Land) [14] This environment is typically dry, experiences sub-zero temperatures, to space during the Lithopanspermia experiment [9,10]; and lichens, Antarctic fungi, bacteria, and and is exposed to ultra-violet radiation, so has been used as a terrestrial analogue for martian cyanobacteria survived 16–18 months in space on the European Technology Exposure Facility’s (EuTEF). DNA; (ii) characterize any changes in cellular ultrastructure that are indicative of stress, damage, or lethality; and (iii) determine whether DNA is sufficiently stable to act as a biosignature for life detection [20,21,32]
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