S., González Kessler, C., Amils, R. and Fernández Remolar, D. (2003) Tirez Lake as a Terrestrial Analog of Europa. Astrobiology, 3: 863–877. Sleep, N.H. and Bird, D.K. (2007) Niches of the

pre-photosynthetic biosphere and geologic preservation of Earth’s earliest biosphere ecology. Geobiology, 5: 101–117. E-mail: ilozada@ccg.​unam.​mx Microbial Diversity of Tirez an Extreme Halophilic Environment, the Case of Ephemeral Conditions M. José Rastoll1, Lilia Montoya1, Nuria Rodríguez2, Ricardo Amils1,2, Irma Marín1 1Departamento de Biología Molecular. Universidad Autónoma de Madrid, 28049. Madrid, Spain; 2Centro de Astrobiología, INTA, 28855. Torrejón de Ardoz, Spain LY294002 Tirez is an inland hypersaline lagoon located in La Mancha, one of the three Iberian Peninsula endorheic arid regions. The continental climate conditions causes its physico-chemical features to be ephemeral, alternating periods of waters dilution, when microbial life proliferates, followed by drought ones, when the brine precipitates generating evaporitic sediments (Prieto-Ballesteros et al., 2003). Tirez lagoon is chemically defined as an athalassohaline environment, since sulfate concentration can reach ten times that of chloride. Most ecological information about hypersaline systems has been generated, however, from thalassohaline systems since, generally,

hypersaline communities are considered as Early Earth models. The primary productivity in these systems relies on prokaryotic KPT-330 mouse microorganisms (Ley et al., 2007), and members of the Eukarya domain are absent or low abundant. Bacterial neuraminidase In contrast, there

are few studies mTOR inhibitor focused on athalassohaline environments and particularly on those suffering of pronounced seasonal changes. In this context, the aim of this study was to reach a better understanding of the biological diversity present in the Tirez athalassohaline lagoon. To characterize the microbial communities inhabiting Tirez lagoon, we made use of molecular biology, as well as classical microorganisms isolation techniques. In both approaches 16S rRNA gene sequence is used as an identification and phylogenetic adscription tool. Phylotypes detected by molecular biology techniques, such as PCR, DGGE and cloning, include Halomonas sp. (Bacteria) in both dry and humid seasons; Halobacterium sp. and Halorubrum sp. (Archaea) only in the dry period and Microcoleus sp. (Cyanobacteria) in the flooded one. Isolates from flooded season were assigned to the Phylum Cyanobacteria: Oscillatoria and Leptolyngbya genera while Dunaliella was identified as the main primary producer in high osmolarity conditions (33% (w/v) of salts) In conclusion, the euryhaline Phylum Proteobacteria was the dominant taxa during high and low salinity periods (5.2% and 33% (w/v) of salts, respectively) and Tirez lagoon does not show significant differences, at the Phylum level, with the microorganisms found in other hypersaline lakes (see e.g., Demergasso et al., 2004). Demergasso et al. (2004).