Active Microbiome Variability in a High Altitude Wetland during Wet and Dry Seasons

Salar del Huasco is a high-altitude wetland situated at 3,800 m. a. s. l. characterized by the presence of diverse aquatic environments such as freshwater spring, ponds and a main lagoon with variable salinity, sometimes reaching >51,000 uS/cm. Previous studies suggest that this ecosystem holds a highly diverse microbial community, however the seasonal variability of their composition is still not well-known. In this study, we determine the variability of bacteria and archaea active composition at different aquatic sites of the wetland during wet and dry seasons (February and July 2012, respectively) through massive sequencing (pyrolibraries) of 16S rRNA and identify potential forcing of their distribution, including environmental and viral abundance changes. The results indicate that microbial communities were highly diverse particularly at pond sites and during the wet season. Pond sites were characterized also by holding a higher number of sequences with non-relative in databases and high viral particles contribution, both variables linearly correlated (r=0.83). Predominant active phyla within archaea were Euryarchaeota followed by Diapherotrites and Thaumarchaeota, whereas within bacteria were Proteobacteria, Bacteroidetes, Cyanobacteria and Verrucomicrobia. Methanomicrobia class associated with methanogenic archaea were the group that contributed greatly to the seasonal variability presented an increased >47% of its abundance between the wet and dry period. Environmental variables such as conductivity and nutrients contributed mainly to the microbial community structure at the different aquatic sites, e.g., nutrients at spring sites, conductivity at lagoon and pond sites, independent on the season. In total, our results suggest that the active microbial community was closely related with the different aquatic sites influenced by conductivity and nutrients, mainly at evaporitic ponds were the microbiome was highly diverse and potentially top-down controlled by viruses.