RT Journal Article SR Electronic T1 Rapid shift in microbial community structure in a neutral hydrothermal hot spring from Costa Rica JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.11.23.395137 DO 10.1101/2020.11.23.395137 A1 Diego Rojas-Gätjens A1 Alejandro Arce-Rodríguez A1 Fernando Puente-Sánchez A1 Roberto Avendaño A1 Eduardo Libby A1 Geraldine Conejo-Barboza A1 Raul Mora-Amador A1 Keilor Rojas A1 Dietmar H. Pieper A1 Max Chavarría YR 2020 UL http://biorxiv.org/content/early/2020/11/25/2020.11.23.395137.abstract AB In this work, we characterize the geochemistry and microbial community of Bajo las Peñas, a neutral (pH 6.5-7.4), hot spring (T = 62.0-68.0°C) located near Turrialba Volcano, Costa Rica. The microbiota at its two sources belongs mainly to the family Aquificae, comprising OTUs closely related to the genera Sulfurihydrogenibium, Thermosulfidibacter, Thermodesulfovibrio and Thermocrinis which is consistent with the presence of moderate levels of sulfate (243-284 mg/L) along the stream. We determined a dramatic shift in the microbial community just a few meters downstream of the sources of the hot spring (15-20 meters), with a change from sulfur related chemoautotrophic (e.g. Sulfurihydrogenibium and an OTU closely related to Thermodesulfovibrio) to chemoheterotrophic prokaryotes (e.g. Meiothermus, Nitrososphaera, Thermoflexus, Thermus). Thus, in this neutral hot spring, the first level of the trophic chain is associated with photosynthesis as well other anaerobic CO2 fixing bacteria. Then, thermotolerant chemoheterotrophic bacteria colonize the environment to degrade organic matter and use fermentative products from the first level of the trophic chain. Our data demonstrate how quickly the microbial community of an ecosystem can change in response to environmental variables and sheds light on the microbial ecology of less common circumneutral pH hot springs.Competing Interest StatementThe authors have declared no competing interest.