Abstract
Extremophiles are organisms capable of adjust, survive or thrive in hostile habitats that were previously thought to be adverse or lethal for life. Chile gathers a wide range of extreme environments: salars, geothermal springs, and geysers located at Altiplano and Atacama Desert, salars and cold mountains in Central Chile, and ice fields, cold lakes and fjords, and geothermal sites in Patagonia and Antarctica. The aims of this review are to describe extremophiles that inhabit main extreme biotopes in Chile, and their molecular and physiological capabilities that may be advantageous for bioremediation processes. After briefly describing the main ecological niches of extremophiles along Chilean territory, this review is focused on the microbial diversity and composition of these biotopes microbiomes. Extremophiles have been isolated in diverse zones in Chile that possess extreme conditions such as Altiplano, Atacama Desert, Central Chile, Patagonia, and Antarctica. Interesting extremophiles from Chile with potential biotechnological applications include thermophiles (e.g., Methanofollis tationis from Tatio Geyser), acidophiles (e.g., Acidithiobacillus ferrooxidans, Leptospirillum ferriphilum from Atacama Desert and Central Chile copper ores), halophiles (e.g., Shewanella sp. Asc-3 from Altiplano, Streptomyces sp. HKF-8 from Patagonia), alkaliphiles (Exiguobacterium sp. SH31 from Altiplano), xerotolerant bacteria (S. atacamensis from Atacama Desert), UV- and Gamma-resistant bacteria (Deinococcus peraridilitoris from Atacama Desert) and psychrophiles (e.g., Pseudomonas putida ATH-43 from Antarctica). The molecular and physiological properties of diverse extremophiles from Chile and their application in bioremediation or waste treatments are further discussed. Interestingly, the remarkable adaptative capabilities of extremophiles convert them into an attractive source of catalysts for bioremediation and industrial processes.
Highlights
Most the well-described forms of life are mainly adapted to face environments with “physiological conditions,” a term described in literature as moderate temperature (10–37◦C), pH ∼ 7, salinity ranging from 0.15 to 0.5 M NaCl, pressure 1 atm and enough water availability (Aguilar et al, 1998; Antranikian et al, 2005)
Extremophiles, can be classified according to the conditions in which they grow: thermophiles and hyperthermophiles (Madigan et al, 2000; Berenguer, 2011), psychrophiles (Siddiqui et al, 2013), acidophiles and alkaliphiles, halophiles (Edbeib et al, 2016), microorganisms that survive in dry environments (Connon et al, 2007) and radiotolerant (UV resistant) extremophiles that are resistant to the permanent exposure to damaging solar radiation (Gabani et al, 2014) (Table 1)
Specific extreme biotopes of Chile are attractive scenarios to study the evolution of microorganisms under extreme conditions, which resemble the islands of the Galapagos Archipelago that provide Darwin inspiring ideas to build up the Theory of Evolution by Natural Selection of macroorganisms based on the divergence of species of birds, especially the Galapagos finches
Summary
Most the well-described forms of life are mainly adapted to face environments with “physiological conditions,” a term described in literature as moderate temperature (10–37◦C), pH ∼ 7, salinity ranging from 0.15 to 0.5 M NaCl, pressure 1 atm and enough water availability (Aguilar et al, 1998; Antranikian et al, 2005). Extremophiles, can be classified according to the conditions in which they grow: thermophiles and hyperthermophiles (organisms growing at temperatures of 45–80◦C and >80◦C, respectively) (Madigan et al, 2000; Berenguer, 2011), psychrophiles (organisms that grow at 9, respectively), halophiles (organisms that require NaCl for growth, in concentration of 200–5,900 mM) (Edbeib et al, 2016), microorganisms that survive in dry environments (water activity < 0.75) (Connon et al, 2007) and radiotolerant (UV resistant) extremophiles that are resistant to the permanent exposure to damaging solar radiation (Gabani et al, 2014) (Table 1). Due to its extremely diverse geography and singular geochemical and climatic conditions, Chile gathers many extreme environments, which may result intolerably hostile or even lethal for most life forms, except for extremophiles (Rampelotto, 2013). Specific extreme biotopes of Chile are attractive scenarios to study the evolution of microorganisms under extreme conditions, which resemble the islands of the Galapagos Archipelago that provide Darwin inspiring ideas to build up the Theory of Evolution by Natural Selection of macroorganisms based on the divergence of species of birds, especially the Galapagos finches
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