Biology subjects

Mora-Amador, R.

Publications and source records attributed to Mora-Amador, R..

3 recordsLinked to original sources

bioRxiv2020

Rapid shift in microbial community structure in a neutral hydrothermal hot spring from Costa Rica

In this work, we characterize the geochemistry and microbial community of Bajo las Penas, a neutral (pH 6.5-7.4), hot spring (T = 62.0-68.0{degrees}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.

microbiology↗

bioRxiv2020

Temperature and elemental sulfur shape microbial communities in two extremely acidic aquatic volcanic environments

Aquatic environments of volcanic origin provide an exceptional opportunity to study the adaptations of microbial communities to early planet life conditions such as high temperatures, high metal concentrations, and low pH. Here, we characterized the prokaryotic communities and physicochemical properties of seepage sites at the bottom of the Poas Volcano crater and the Agrio River, two geologically related extremely acidic environments located in the Central Volcanic mountain range of Costa Rica. Both locations hold a very low pH (pH 1.79-2.20) and have high sulfate and iron concentrations (Fe = 47-206 mg/L, SO42- = 1170-2460 mg/L measured as S), but significant differences in their temperature (90.0-95.0{degrees}C in the seepages at Poas Volcano versus 19.1-26.6 {degrees}C in Agrio River) and in the abundance of elemental sulfur. Based on the analysis of 16S rRNA gene sequences, we determined that Sulfobacillus spp., sulfur-oxidizing bacteria, represented more than half (58.4-78.4%) of the sequences in Poas Volcano seepage sites, while Agrio River was dominated by the iron- and sulfur-oxidizing Leptospirillum (7.4-55.5%) and members of the archeal order Thermoplasmatales (16.0-58.2%). Both environments share some chemical characteristics and part of their microbiota, however the temperature and the presence of reduced sulfur are likely the main distinguishing feature ultimately shaping their microbial communities. Our data suggest that in the Poas Volcano-Agrio River system there is a common metabolism but with specialization of species that adapt to the physicochemical conditions of each environment.

microbiology↗

bioRxiv2019

Untapped microbial composition along a horizontal oxygen gradient in a Costa Rican volcanic influenced acid rock drainage system

Based on the analysis of 16S rRNA gene metabarcoding, here we report the shift in the microbial community structure along a horizontal oxygen gradient (0.40-6.06 mg L-1) in a volcanic influenced acid rock drainage (VARD) environment, known as San Cayetano (Cartago, Costa Rica; pH =2.94-3.06, sulfate ~0.87-1.19 g L-1, iron ~35-61 mg L-1). This VARD is dominated by microorganisms involved in the geochemical cycling of iron, sulfur and nitrogen; however, the identity of the species changes with the oxygen gradient along the river course. The anoxic spring of San Cayetano is dominated by a putative anaerobic sulfate-reducing Deltaproteobacterium as well as sulfur-oxidizing bacteria (such as Acidithiobacillus or Sulfobacillus), which favor the process of dissolution of sulfide minerals and oxidation of H2S. In oxic conditions, aerobic iron-oxidizers (Leptospirillum, Acidithrix, Ferritrophicum, Ferrovum) and heterotrophic bacteria (Burkholderiaceae Betaproteobacterium, Trichococcus, Acidocella) were identified among others. Thermoplasmatales archaea closely related to environmental phylotypes found in other ARD/AMD niches were also found throughout the entire ecosystem. This work describes the changes in bacterial diversity, and possible metabolic activities occurring along a horizontal oxygen gradient in a volcanic influenced acid rock drainage system.

microbiology↗