Prokaryotic and viral community of the sulfate‐rich crust from Peñahueca ephemeral lake, an astrobiology analogue

Abstract

Summary Peñahueca is an athalassohaline hypersaline inland ephemeral lake originated under semiarid conditions in the central Iberian Peninsula (Spain). Its chemical composition makes it extreme for microbial life as well as a terrestrial analogue of other planetary environments. To investigate the persistence of microbial life associated with sulfate‐rich crusts, we applied cultivation‐independent methods (optical and electron microscopy, 16S rRNA gene profiling and metagenomics) to describe the prokaryotic community and its associated viruses. The diversity for Bacteria was very low and was vastly dominated by endospore formers related to Pontibacillus marinus of the Firmicutes phylum. The archaeal assemblage was more diverse and included taxa related to those normally found in hypersaline environments. Several ‘metagenome assembled genomes’ were recovered, corresponding to new species of Pontibacillus, several species from the Halobacteria and one new member of the Nanohaloarchaeota. The viral assemblage, although composed of the morphotypes typical of high salt systems, showed little similarity to previously isolated/reconstructed halophages. Several putative prophages of Pontibacillus and haloarchaeal hosts were identified. Remarkably, the Peñahueca sulfate‐rich metagenome contained CRISPR‐associated proteins and repetitions which were over 10‐fold higher than in most hypersaline systems analysed so far.

A Review on Viral Metagenomics in Extreme Environments

“…Functional viral metagenomics focuses on exploring viral diversity to discover novel genes. Extreme environments harbor an enormous diversity of unknown viruses (Desnues et al, 2008; Dinsdale et al, 2008; Williamson et al, 2008; Rosario and Breitbart, 2011; Kristensen et al, 2012; Atanasova et al, 2016; Gudbergsdóttir et al, 2016; Nigro et al, 2017; Zablocki et al, 2017a, b; Sharma et al, 2018; Liu et al, 2019; Martin-Cuadrado et al, 2019; Mizuno et al, 2019; Roux et al, 2019) and, consequently, a potentially large number of unknown viral proteins. Functional viral metagenomics in these niches show a limited progress, with few reported recent advances (Schoenfeld et al, 2009; Schmitz et al, 2010; Moser et al, 2012; Heller et al, 2019) (Figure 8).…”

“…Some families of the order Caudovirales are ubiquitous and the most abundant were the Siphoviridae , Myoviridae , and Podoviridae as expected, since the viruses that belong to these families infect a wide range of bacterial hosts from more than 140 prokaryotic genera (Konstantinidis et al, 2009; Hurwitz et al, 2013; Danovaro et al, 2016; Graham et al, 2019). It has been considered that the information from whole metagenomic analysis can give clues of potential model microorganisms to host virus replication, through the analysis of the Clusters of Regularly Interspaced Short Palindromic Repeats (CRISPR) loci from the cellular fraction of the metagenomes, that have been isolated from extreme environments (Gudbergsdóttir et al, 2016; Sharma et al, 2018; Liu et al, 2019; Martin-Cuadrado et al, 2019).…”

Viral Community Structure and Potential Functions in the Dried-Out Aral Sea Basin Change along a Desiccation Gradient

“…In general, viral diversity in extreme environments is still largely unexplored ( 26 , 27 ). In comparison to other hyperarid and saline environments, i.e., the Atacama Desert ( 28 , 29 ) and the Peñahueca shallow saline lake ( 30 ), a relatively high number of vOTUs was detected in the Aral Sea basin. Viruses that were linked to distinct hosts contained auxiliary metabolic genes (AMGs) that may play roles in the biogeochemical cycles, competitiveness, and resilience against environmental stress of their putative hosts.…”

In situ organic biosignature detection techniques for space applications

“…These bacteria can subsequently rapidly be detected and identified in unknown samples (Parro et al, 2005). The multiplex sandwich array has mainly been used to pursue detecting microbial communities, which has been demonstrated multiple times with extracts of samples from extreme environments such as the Atacama Desert (Parro et al, 2011a;Blanco et al, 2013;Crits-Christoph et al, 2013;Fernández-Martínez et al, 2019), Antarctica (Lezcano et al, 2019), and other sites (Martin-Cuadrado et al, 2019). Unlike other techniques discussed in this review, immunoassays with receptors against cells do not require a cell lysing step prior to detection (Rivas et al, 2008).…”