Examinando por Autor "Eissler, Yoanna"

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    High nutrient requirement on the photosynthetic performance of a diatom species of the genus Nitzschia (Bacillariophyta) isolated from the high-altitude wetland, Salar de Huasco, Chile
    (Wiley, 2025) Eissler, Yoanna; Anabalon, Jeremy; Celis-Pla, Paula S. M; Kieft, Brandon; Junier, Pilar; Rivera, Patricio; Cruces, Fabiola; Ascencio, Enrique; Dorador, Cristina; Molina, Veronica
    This study characterizes the ecophysiological responses andgrowth dynamics of Nitzschia palea isolated from Salar deHuasco, Chile, a high-altitude wetland located at 3800 mabove sea level. The culture was maintained at 17_x000E_C undercool-white fluorescent light with a 14:10 h light/dark photo-cycle and a photon flux of 50 μmol photons m_x0003_2 s_x0003_1 . The dia-tom was identified morphologically and genetically, withphylogenetic analysis confirming its close relationship toknown N. palea strains. Photophysiological responses weremeasured along with a series of media and temperature condi-tions in N. palea strain. Modified f/2 media supplementedwith different concentrations of Si, Se and vitamins weretested. Subsequently, growth in the double-Si f/2 media wasassessed at three different temperatures. Lastly, the diatomstrain was incubated at 17_x000E_C and 27–29_x000E_C in f/2 + double-Si(NN: non-extra nutrient addition) and a highly eutrophic stateof f/2 (WN: with nutrient enrichment addition). The highestgrowth was observed using the f/2 media WN at 17_x000E_C (day5, 4.46 _x0004_ 105 _x0005_ 3.15 _x0004_ 104 SD cells mL_x0003_1 ). Temperaturesignificantly influenced growth; 17_x000E_C supported higher celldensities and more stable photosynthetic parameters com-pared 27–29_x000E_C. Nutrient enrichment further enhanced photo-synthetic efficiency (αETR) and maximal quantum yield(Fv/F m), particularly under control temperature conditions.Photosynthetic performance, assessed via rapid light-responsecurves, showed significant temperature and nutrient depen-dent variation. Nitzschia palea cultures at 27–29_x000E_C exhibitedincreased in relative maximal ETR (rETR max ,184.1μmol m_x0003_2 s_x0003_1 ) compared to control conditions. In nutrientenriched treatments, photosynthetic efficiency peaked on day5, but declined by day 8. These findings highlight theadaptive capacity of N. palea to fluctuating environmentalconditions and underscore its potential as a model organismfor studying diatom responses to nutrient and temperaturestress in extreme ecosystems
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    Peatland Pond Microbiome and Biogeochemical Responses to Solar Radiation Extremes in a High-Altitude Wetland, Salar de Huasco, Chile
    (MDPI, 2025) Eissler, Yoanna; Yanez-Montalvo, Alfredo; Celis-Pla, Paula S. M; Cornejo-D'Ottone, Marcela; Trabal, Andres; Dorador, Cristina; Piccini, Claudia; Falcon, Luisa I; Romero, Carlos; Aguilar-Munoz, Polette; Molina, Veronica
    High-altitude wetland holds unique peatland ponds subjected to extreme diel environmental condition changes. Herein, we evaluate the response of photoautotrophic and nitrification activities and compare it with bacteria and archaea composition shifts in sediment and water changes during key hours of the day. Results indicate the presence of photo-inhibition, including ammonia oxidizers, but a high recovery of photosynthetic activities in the microbial mat and of potential specific functional groups towards the afternoon. The microbial community was composed of 45 phyla, mainly proteobacteria from Alpha-, Delta-, and Gammaproteobacteria and Bacteroidota in the water and sediments, and these later groups were notoriously enriched during the afternoon. The microbial community composition changes were associated with chlorophyll a, nutrients, and greenhouse gases reservoir variability, including methane potential release towards the atmosphere at hours of high radiation. Peatland pond microbial communities and their biogeochemical contribution change in a complex interplay coupled by time to environmental conditions predominantly driven by the extreme solar radiation.
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    Secondary metabolites with antimicrobial activity produced by thermophilic bacteria from a high-altitude hydrothermal system
    (Frontiers Media SA, 2024) Pardo Esté, Coral; Cortés, Johanna; Castro Severyn, Juan; Pérez, Vilma; Henriquez Aedo, Karem; Cuadros, Fabian; Yañez, Carolina; Cuadros Orellana, Sara; Dorador, Cristina; Molina, Veronica; Eissler, Yoanna; Paquis, Pablo; Jeffrey, Wade H.; Pozo, Patricia; Pérez, Pablo A.; Hengst, Martha B.
    Thermophilic microorganisms possess several adaptations to thrive in high temperature, which is reflected as biosynthesis of proteins and thermostable molecules, isolation and culture represent a great methodological challenge, therefore High throughput sequencing enables screening of the whole bacterial genome for functional potential, providing rapid and cost-effective information to guide targeted cultures for the identification and characterization of novel natural products. In this study, we isolated two thermophilic bacterial strains corresponding to Bacillus LB7 and Streptomyces LB8, from the microbial mats in the Atacama Desert. By combining genome mining, targeted cultures and biochemical characterization, we aimed to identify their capacity to synthesize bioactive compounds with antimicrobial properties. Additionally, we determined the capability to produce bioactive compounds under controlled in vitro assays and detected by determining their masses by Thin-Layer Chromatography/Mass Spectrometry (TLC/MS). Overall, both isolates can produce antimicrobial (e.g., Myxalamide C by-product) and antioxidants (e.g. Dihydroxymandelic Acid, Amide biotine and Flavone by-products) compounds. Bacillus LB7 strain possesses a more diverse repertoire with 51.95% of total metabolites unmatched, while Streptomyces LB8 favors mainly antioxidants, but has over 70% of unclassified compounds, highlighting the necessity to study and elucidate the structure of novel compounds. Based on these results, we postulate that the uncultured or rare cultured thermophiles inhabiting high-altitude hydrothermal ecosystems in the Atacama Desert offer a promising opportunity to the study of novel microbial bioactive compounds.