High-Up: A Remote Reservoir of Microbial Extremophiles in Central Andean Wetlands

Abstract

The Central Andes region displays unexplored ecosystems of shallow lakes and salt flats at mean altitudes of 3700 m. Being isolated and hostile, these so-called “High-Altitude Andean Lakes” (HAAL) are pristine and have been exposed to little human influence. HAAL proved to be a rich source of microbes showing interesting adaptations to life in extreme settings (poly-extremophiles) such as alkalinity, high concentrations of arsenic and dissolved salts, intense dryness, large daily ambient thermal amplitude, and extreme solar radiation levels. This work reviews HAAL microbiodiversity, taking into account different microbial niches, such as plankton, benthos, microbial mats and microbialites. The modern stromatolites and other microbialites discovered recently at HAAL are highlighted, as they provide unique modern—though quite imperfect—analogs of environments proxy for an earlier time in Earth's history (volcanic setting and profuse hydrothermal activity, low atmospheric O2 pressure, thin ozone layer and high UV exposure). Likewise, we stress the importance of HAAL microbes as model poly-extremophiles in the study of the molecular mechanisms underlying their resistance ability against UV and toxic or deleterious chemicals using genome mining and functional genomics. In future research directions, it will be necessary to exploit the full potential of HAAL poly-extremophiles in terms of their biotechnological applications. Current projects heading this way have yielded detailed molecular information and functional proof on novel extremoenzymes: i.e., DNA repair enzymes and arsenic efflux pumps for which medical and bioremediation applications, respectively, are envisaged. But still, much effort is required to unravel novel functions for this and other molecules that dwell in a unique biological treasure despite its being hidden high up, in the remote Andes.

Bacterial Active Community Cycling in Response to Solar Radiation and Their Influence on Nutrient Changes in a High-Altitude Wetland

“…These phyla are commonly detected in DNA extracted from the water of high-altitude ecosystems from the central Andes (Albarracin et al, 2015), including previous diversity studies using 16S RNA gene cloning for Salar de Huasco (Dorador et al, 2008b, 2009, 2013). Thus, our findings based on 16S rRNA pyrosequencing supports previous studies and given that our results originate from cDNA indicate that wide diversity of phyla previously identified are not only present, but also potentially active.…”

“…Microbial life in these ecosystems is notably highly diverse, characterized by novel groups of prokaryotes, and includes the conspicuous presence of microbial mats (Dorador et al, 2008a,b, 2009, 2013). Highland aquatic ecosystems such as the Altiplano and the high lakes of the Tibetan plateau represent hotspots of microbial life, and can be considered as model ecosystems to study the response of microorganisms to environmental gradients (Jiang et al, 2009; Hu et al, 2010; Kang et al, 2010; Albarracin et al, 2015). …”

Microbial Activity Response to Solar Radiation across Contrasting Environmental Conditions in Salar de Huasco, Northern Chilean Altiplano

“…Biological communities located at high altitude endure extreme conditions such as high daily temperature variability and high incident solar radiation (Rothschild and Mancinelli, 2001; Catalán et al, 2006; Albarracín et al, 2015a,b). In addition, high altitude saline wetlands from the Andean Altiplano present contrasting mineral composition at small spatial scales (Acosta and Custodio, 2008; Risacher and Fritz, 2009; Uribe et al, 2015) that range from freshwater to hypersaline conditions, as well as from limiting to high nutrient concentrations (Dorador et al, 2008b, 2010).…”

“…In addition, high altitude saline wetlands from the Andean Altiplano present contrasting mineral composition at small spatial scales (Acosta and Custodio, 2008; Risacher and Fritz, 2009; Uribe et al, 2015) that range from freshwater to hypersaline conditions, as well as from limiting to high nutrient concentrations (Dorador et al, 2008b, 2010). While biodiversity of higher trophic levels is low in extreme environments (Guerrero et al, 2013), there is evidence that lakes located above 2000 m (e.g., Tibet, Pyrenean, or Andean lakes) hold a large microbial diversity (Wang et al, 2011; Triadó-Margarit and Casamayor, 2012; Albarracín et al, 2015a,b) in association with environmental heterogeneity.…”

“…One of the variables that define high altitude systems as extreme environments for life is solar radiation (Rothschild and Mancinelli, 2001; Piacentini et al, 2003; Cordero et al, 2014; Albarracín et al, 2015a,b). Low zenith angle and high altitude result in incident solar radiation that would be detrimental for aquatic microbial productivity at sea level (Helbling et al, 2001; Sommaruga, 2001; Alonso-Saez et al, 2006; Santos et al, 2012) and could be enhanced by thin ozone and reflectance by clouds and salt (Lovengreen et al, 2005; Häder et al, 2015).…”