In this study we aimed to compare the mineralogical, thermal, physicochemical, and biological characteristics of recent organic carbon-rich sediments (‘sapropels’) from three geographically distant Romanian lakes (Tekirghiol and Amara, SE Romania, and Ursu, Central Romania) with distinct hydrogeochemical origins, presently used for pelotherapy. The investigated lakes were classified as inland brackish Na-Cl-sulfated type (Amara), coastal moderately saline and inland hypersaline Na-Cl types (Tekirghiol and Ursu, respectively). The settled organic matter is largely composed of photosynthetic pigments derived from autochthonous phytoplankton. Kerogen was identified in the sapropel of coastal Tekirghiol Lake suggesting its incipient maturation stage. The mineral composition was fairly similar in all sapropels and mainly consisted of quartz, calcite, and aragonite. Smectite, illite, mixed layer smectite/illite appeared as major clay components. Potentially toxic elements were found in low concentrations. The physical properties (i.e., specific heat, thermal conductivity and retentivity) and cation exchange capacity are comparable to other peloids used for therapy. This study is the first comprehensive multi-approached investigation of the geochemical nature of recent sapropels in Romanian saline lakes and thus contributes to expanding our knowledge on the origin and physicochemical qualities of organic matter-rich peloids with therapeutic uses.

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Saline aquatic systems include inland and marine-derived lakes, solar salterns, or temporary inland saline ponds. Despite their high salinity, these ecosystems are inhabited by diverse microbial communities driving full biogeochemical cycling of main elements. To date, numerous salt-loving (or 'halophilic') environmental strains with metabolic traits of applicative interest belonging to all Domains of Life (Bacteria, Archaea, Eukarya) have been isolated from saline aquatic systems. The aim of the present work is to briefly review some of the most relevant achievements in the bioprospecting of saline aquatic systems for compounds and metabolic capabilities with potential uses in the environmental, industrial, and food biotechnologies. Additionally, the successful stories of current commercial exploitations of a few halotolerant (e.g., the bacterium Halomonas elongata), halophilic (e.g., the green algae Dunaliella sp.), and haloalkaliphilic microbes (e.g., the sulfur-oxidizing bacteria of genus Thioalkalivibrio sp.) are overviewed.

The origin of the eukaryotic cell and its shared evolutionary history with Archaea are among the hottest topics in modern biology. Recent improvements in cultureindependent genomics and phylogenomic analyses provided compelling evidence in support of the emergence of eukaryotes from within the Archaea. An important step towards revealing the identity and nature of the archaeal ancestor was made following metagenomics-based discovery of the Asgardarchaeota superphylum, a group of uncultivated archaea consisting of Loki-, Thor-, Heimdall-and Odinarchaeia. Their recognition as the closest extant relatives of the eukaryotes has reignited a decades-old debate regarding the topology of the Tree of Life. Moreover, genomic investigations of Asgardarchaeota revealed a plethora of "Eukaryote Signature Proteins" (ESPs), previously thought to be unique to eukaryotes, which may help shed light on the molecular events in early eukaryogenesis. In this work, we briefly review current knowledge about the geographical distribution, phylogeny, ESP content and metabolic capabilities of the highly diverse Asgardarchaeota in an attempt to picture the lifestyle and early evolution of eukaryotes.