Abstract
Polar volcanoes harbor unique conditions of extreme temperature gradients capable of selecting different types of extremophiles. Deception Island is a marine stratovolcano located at Maritime Antarctica that is notable for its pronounced temperature gradients over very short distances, reaching values up to 100 °C in the fumaroles, and subzero temperatures next to the glaciers. Due to these characteristics, Deception can be considered an interesting analogue of extraterrestrial environments. Our main goal in this study was to isolate thermophilic and psychrophilic bacteria from sediments associated with fumaroles and glaciers from two geothermal sites in Deception Island, comprising temperatures between 0 and 98 °C, and to evaluate their survivability to desiccation and UV-C radiation. Our results revealed that culturable thermophiles and psychrophiles were recovered among the extreme temperature gradient in Deception volcano, which indicates that these extremophiles remain alive even when the conditions do not comprise their growth range. The viability of culturable psychrophiles in hyperthermophilic environments is still poorly understood and our work showed the importance of future studies about their survival strategies in high temperatures. Finally, the spore-forming thermophilic isolates which we found have displayed good survival to desiccation and UV-C irradiation, which suggests their potential to be further explored in astrobiological studies.
Highlights
Polar volcanoes represent unique regions on Earth where all temperature-adapted bacteria coexist and possibly interact in the same environment due to the pronounced temperature gradient (Amenábar et al 2013)
We reported the presence of several extremophiles-related sequences among extreme temperature gradients in Deception (Bendia et al 2018)
Our results showed that isolates related to thermophilic and psychrophilic groups remain alive among the extreme temperature gradients in Deception Island volcano, even though the conditions do not comprise their growth range
Summary
Polar volcanoes represent unique regions on Earth where all temperature-adapted bacteria (e.g., thermophiles, mesophiles, and psychrophiles) coexist and possibly interact in the same environment due to the pronounced temperature gradient (Amenábar et al 2013). Deception Island is a marine stratovolcano located at Maritime Antarctica that is notable for its extreme steep temperature gradients, since its active fumaroles reach values of 100 °C, whereas half of the island is covered by glaciers (Rey et al 1995; Herbold et al 2014). These characteristics make Deception an interesting analogue of extraterrestrial environments, such as Mars’s extinct volcanoes and Enceladus’s cryovolcanoes (Soo et al 2009; Sekine et al 2015). The isolation and recovery of living cells from extreme environments allow us to understand their survival strategies under simulated extraterrestrial conditions
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