Facultad de Ciencias del Mar y Recursos Biológicos

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Response to static magnetic field-induced stress in scenedesmus obliquus and nannochloropsis gaditana
(MDPI, 2021) Serrano, Génesis; Miranda-Ostoijc, Carol; Ferrada, Pablo; Wulff-Zotelle, Cristian; Maureira, Alejandro; Fuentealba, Edward; Gallardo, Karem; Zapata, Manuel; Rivas, Mariella
Magnetic fields in biological systems is a promising research field; however, their application for microalgae has not been fully exploited. This work aims to measure the enzymatic activity and non-enzymatic activity of two microalgae species in terms of superoxide dismutase (SOD), catalase (CAT), and carotenoids, respectively, in response to static magnetic fields-induced stress. Two magnet configurations (north and south) and two exposure modes (continuous and pulse) were applied. Two microalgae species were considered, the Scenedesmus obliquus and Nannochloropsis gaditana. The SOD activity increased by up to 60% in S. obliquus under continuous exposure. This trend was also found for CAT in the continuous mode. Conversely, under the pulse mode, its response was hampered as the SOD and CAT were reduced. For N. gaditana, SOD increased by up to 62% with the south configuration under continuous exposure. In terms of CAT, there was a higher activity of up to 19%. Under the pulsed exposure, SOD activity was up to 115%. The CAT in this microalga was increased by up to 29%. For N. gaditana, a significant increase of over 40% in violaxanthin production was obtained compared to the control, when the microalgae were exposed to SMF as a pulse. Depending on the exposure mode and species, this methodology can be used to produce oxidative stress and obtain an inhibitory or enhanced response in addition to the significant increase in the production of antioxidant pigments.
Inactivated Vaccine-Induced SARS-CoV-2 Variant-SpeciﬁcImmunity in Children
(American Society for Microbiology, 2022) Soto, Jorge A.; Melo González, Felipe; Gutierrez Vera, Cristián; Schultz, Bárbara M.; Berríos Rojas, Roslye V.; Rivera Pérez, Daniela; Piña Iturbe, Alejandro; Hoppe Elsholz, Guillermo; Duarte, Luisa F.; Vázquez, Yaneisi; Moreno Tapia, Daniela; Ríos, Mariana; Palacios, Pablo A.; Garcia Betancourt, Richard; Santibañez, Álvaro; Pacheco, Gaspar A.; Mendez, Constanza; Andrade, Catalina A.; Silva, Pedro H.; Diethelm Varela, Benjamín; Astudillo, Patricia; Calvo, Mario; Cárdenas, Antonio; González, Marcela; Goldsack, Macarena; Gutiérrez, Valentina; Potin, Marcela; Schilling, Andrea; Tapia, Lorena I.; Twele, Loreto; Villena, Rodolfo; Grifoni, Alba; Sette, Alessandro; Weiskopf, Daniela; Fasce, Rodrigo A.; Fernández, Jorge; Mora, Judith; Ramírez, Eugenio; Gaete Argel, Aracelly; Acevedo, Mónica L.; Valiente Echeverría, Fernando; Soto Rifo, Ricardo; Retamal Díaz, Angello; Muñoz Jofré, Nathalia; PedCoronaVac03CL Study Group; Meng, Xing; Xin, Qianqian; Alarcón Bustamante, Eduardo; González Aramundiz, José V.; Le Corre, Nicole; Álvarez Figueroa, María Javiera; González, Pablo A.; Abarca, Katia; Perret, Cecilia; Carreño, Leandro J.; Bueno, Susan M.; Kalergis, Alexis M.
Multiple vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been evaluated in clinical trials. However, trials addressing the immune response in the pediatric population are scarce. The inactivated vaccine CoronaVac has been shown to be safe and immunogenic in a phase 1/2 clinical trial in a pediatric cohort in China. Here, we report interim safety and immunogenicity results of a phase 3 clinical trial for CoronaVac in healthy children and adolescents in Chile. Participants 3 to 17 years old received two doses of CoronaVac in a 4-week interval until 31 December 2021. Local and systemic adverse reactions were registered for volunteers who received one or two doses of CoronaVac. Whole-blood samples were collected from a subgroup of 148 participants for humoral and cellular immunity analyses. The main adverse reaction reported after the first and second doses was pain at the injection site. Four weeks after the second dose, an increase in neutralizing antibody titer was observed in subjects relative to their baseline visit. Similar results were found for activation of specific CD41 T cells. Neutralizing antibodies were identified against the Delta and Omicron variants. However, these titers were lower than those for the D614G strain. Importantly, comparable CD41 T cell responses were detected against these variants of concern. Therefore, CoronaVac is safe and immunogenic in subjects 3 to 17 years old, inducing neutralizing antibody secretion and activating CD41 T cells against SARS-CoV-2 and its variants. (This study has been registered at ClinicalTrials .gov under no. NCT04992260.)
Different Safety Pattern of an Inactivated SARS-CoV-2 Vaccine (CoronaVac®) According to Age Group in a Pediatric Population from 3 to 17 Years Old, in an Open-Label Study in Chile
(MDPI, 2023) Le Corre, Nicole; Abarca, Katia; Astudillo, Patricio; Potin, Marcela; López, Sofía; Goldsack, Macarena; Valenzuela, Vania; Schilling, Andrea; Gaete, Victoria; Rubio, Lilian; Calvo, Mario; Twele, Loreto; González, Marcela; Fuentes, Daniela; Gutiérrez, Valentina; Reyes, Felipe; Tapia, Lorena I.; Villena, Rodolfo; Retamal-Díaz, Angello; Cárdenas, Antonio; Alarcón-Bustamante, Eduardo; Meng, Xing; Xin, Qianqian; González-Aramundiz, José V.; Álvarez-Figueroa, María Javiera; González, Pablo A.; Bueno, Susan M.; Soto, Jorge A.; Perret, Cecilia; Kalergis, Alexis M.
During the COVID-19 pandemic, the importance of vaccinating children against SARS-CoV- 2 was rapidly established. This study describes the safety of CoronaVac® in children and adolescents between 3- and 17-years-old in a multicenter study in Chile with two vaccine doses in a 4-week interval. For all participants, immediate adverse events (AEs), serious AEs (SAEs), and AEs of special interest (AESIs) were registered throughout the study. In the safety subgroup, AEs were recorded 28 days after each dose. COVID-19 surveillance was performed throughout the study. A total of 1139 individuals received the first and 1102 the second dose of CoronaVac®; 835 were in the safety subgroup. The first dose showed the highest number of AEs: up to 22.2% of participants reported any local and 17.1% systemic AE. AEs were more frequent in adolescents after the first dose, were transient, and mainly mild. Pain at the inoculation site was the most frequent AE for all ages. Fever was the most frequent systemic AE for 3–5 years old and headache in 6–17 years old. No SAEs or AESIs related to vaccination occurred. Most of the COVID-19 cases were mild and managed as outpatients. CoronaVac® was safe and well tolerated in children and adolescents, with different safety patterns according to age.
Insights into the diversity and survival strategies of soil bacterial isolates from the Atacama Desert
(Frontiers Media SA, 2024) Reverdy, Alicyn; Hathaway, Daniel; Jha, Jessica; Michaels, Gabriel; Sullivan, Jeffrey; Diaz McAdoo, Daniela; Riquelme, Carlos; Chai, Yunrong; Godoy Carter, Veronica
The Atacama Desert, the driest, with the highest radiation, and one of the most ancient deserts in the world, is a hostile environment for life. We have a collection of 74 unique bacterial isolates after cultivation and confirmation by 16S rRNA gene sequencing. Pigmentation, biofilm formation, antimicrobial production against Escherichia coli MG1655 and Staphylococcus aureus HG003,and antibiotic resistance were assessed on these isolates. We found that approximately a third of the colonies produced pigments, 80% of isolates formed biofilms, many isolates produce growth inhibiting activities against E. coliand/orS. aureus, and many were resistant to antibiotics. The functional characterization of these isolates gives us insight into the adaptive bacterial strategies in harsh environments and enables us to learn about their possible use in agriculture,healthcare, or biotechnology.
Blowin’ in the Wind: Mapping the Dispersion of Metal(loid)s From Atacama Mining
(Advancing Earth and Space Sciences, 2024) Zanetta-Colombo, Nicolás, C.; Manzano, Carlos A.; Brombierstäudl, Dragmar; Fleming, Zoë L.; Gayo, Eugenia M.; Rubinos, David A.; Jerez, Óscar; Valdés, Jorge; Prieto, Manuel; Nüsser, Marcus
The Atacama Desert's naturally elevated metal(loid)s pose a unique challenge for assessing the environmental impact of mining, particularly for indigenous communities residing in these areas. This study investigates how copper mining influences the dispersion of these elements in the wind-transportable fraction (<75 mu m) of surface sediments across an 80 km radius. We employed a multi-pronged approach, utilizing spatial modeling to map element distributions, exponential decay analysis to quantify concentration decline with distance, regime shift modeling to identify dispersion pattern variations, and pollution assessment to evaluate impact. Our results reveal significant mining-driven increases in surface concentrations of copper (Cu), molybdenum (Mo), and arsenic (As). Notably, within the first 20 km, concentrations peaked at 1,016 mg kg(-1) for Cu, 31 mg kg(-1) for Mo, and a remarkable 165 mg kg(-1) for As. Cu and Mo displayed significant dispersion, extending up to 50 km from the source. However, As exhibited the most extensive reach, traveling up to 70 km downwind, highlighting the far-reaching ecological footprint of mining operations. Mineralogical analyses corroborated these findings, identifying mining-related minerals in surface sediments far beyond the immediate mining area. Although pollution indices based on the proposed Local Geochemical Background reveal significant contamination across the study area, establishing accurate pre-industrial baseline values is essential for a more reliable assessment. This study challenges the concept of "natural pollution" by demonstrating that human activities exacerbate baseline metal(loid)s levels. Expanding monitoring protocols is imperative to comprehensively assess the combined effects of multiple emission sources, including mining and natural processes, in safeguarding environmental and human health for future generations.
Metals and metaloid preserved in marine sediments of an industrial complex of central Chile. Environmental assessment using different background values
(ELSEVIER, 2024) Valdés Saavedra, Jorge; Quiroga, Eduardo
This work examines the distribution of metals(oid) in coastal sediments of the Concon-Quintero industrial complexes (central Chile), and evaluates the environmental condition of this zone, using some environmental indexes and different global and local background values. The Index of geoaccumulation and the Enrichment Factor were different depending on the background values used to calculate them. Only Mo and Pb, simultaneously show both an enrichment, and some degree of pollution problem, with all backgrounds utilized. Three of the four background values used in this work to calculates the Pollution Load Index suggests a polluted condition of the bottom environment. The spatial distribution, the results of environmental indices and the comparison with local environmental legislation suggests that Pb is introduced to the marine system by industrial activities. The result of both, SQG and m-ERM-Q suggest that metals preserved in the sediments are a threat to the benthic life, especially in the Concon-Ritoque zone, where the highest values were recorded. These results suggest a notorious influence of the Aconcagua river on the metal accumulation in the coastal zone.
MICP mediated by indigenous bacteria isolated from tailings for biocementation for reduction of wind erosion
(Frontiers Media SA, 2024) Maureira, Alejandro; Zapata, Manuel; Olave, Jorge; Jeison, David; Wong, Liey-Si; Panico, Antonio; Hernández, Pía
In this study, native ureolytic bacteria were isolated from copper tailings soils to perform microbial-induced carbonate precipitation (MICP) tests and evaluate their potential for biocement formation and their contribution to reduce th dispersion of particulate matter into the environment from tailings containing potentially toxic elements. It was possible to isolate a total of 46 bacteria; among them only three showed ureolytic activity: Priestia megaterium T130-1, Paenibacillus sp. T130-13 and Staphylococcus sp. T130-14. Biocement cores were made by mixing tailings with the isolated bacteria in presence of urea, resulting similar to those obtained with Sporosarcina pasteurii and Bacillus subtilis used as positive control. Indeed, XRD analysis conducted on biocement showed the presence of microcline (B. subtilis 17%; P. megaterium 11. 9%), clinochlore (S.pasteurii, 6.9%) and magnesiumhornblende (Paenibacillus sp. 17.8%; P. megaterium 14.6%); all these compounds were not initially present in the tailings soils. Moreover the presence of calcite (control 0.828%; Paenibacillus sp. 5.4%) and hematite (control 0.989%; B. subtilis 6.4%) was also significant unlike the untreated control. The development of biofilms containing abundant amount of Ca, C, andOon microscopic soil particles was evidenced by means of FE-SEMEDX and XRD. Wind tunnel tests were carried out to investigate the resistance of biocement samples, accounted for a mass loss five holds lower than the control, i.e., the rate of wind erosion in the control corresponded to 82 g/m2h while for the biocement treated with Paenibacillus sp. it corresponded to only 16.371 g/m2h. Finally, in compression tests, the biocement samples prepared with P. megaterium (28.578 psi) and Paenibacillus sp. (28.404 psi) showed values similar to those obtained with S. pasteurii (27.102 psi), but significantly higher if compared to the control (15.427 psi), thus improving the compression resistance capacity of the samples by 85.2% and 84.1% with respect to the control. According to the results obtained, the biocement samples generated with the native strains showed improvements in the mechanical properties of the soil supporting them as potential candidates in applications for the stabilization of mining liabilities in open environments using bioaugmentation strategies with native strains isolated from the same mine tailing.
The Chilean COVID-19 Genomics Network Biorepository: A Resource for Multi-Omics Studies of COVID-19 and Long COVID in a Latin American Population
(MDPI, 2024) Signore, Iskra A.; Donoso, Gerardo; Bocchieri, Pamela; Tobar-Calfucoy, Eduardo A.; Yáñez, Cristian E.; Carvajal-Silva, Laura; Silva, Andrea X.; Otth, Carola; Cappelli, Claudio; Valenzuela Jorquera, Héctor; Zapata Contreras, Daniela; Espinosa Parrilla, Yolanda; Zúñiga Pacheco, Paula; Fuentes Guajardo, Macarena; Monardes Ramírez, Virginia A.; Kochifas Velasquez, Pia; Muñoz, Christian A.; Dorador, Cristina; García Araya, Jonathan; Campillay Véliz, Claudia P.; Echeverria, Cesar; Santander, Rodolfo Alejandro; Cerpa, Leslie C.; Martínez, Matías F.; Quiñones, Luis Abel; Lamoza Galleguillos, Eduardo Roberto; Saez Hidalgo, Juan; Nova-Lamperti, Estefanía; Sanhueza, Sergio; Giacaman, Annesi; Acosta Jamett, Gerardo; Verdugo, Cristóbal; Plaza, Anita; Verdugo, Claudio; Selman, Carolina; Verdugo, Ricardo Alejandro; Colombo, Alicia
Although a lack of diversity in genetic studies is an acknowledged obstacle for personalized medicine and precision public health, Latin American populations remain particularly understudied despite their heterogeneity and mixed ancestry. This gap extends to COVID-19 despite its variability in susceptibility and clinical course, where ethnic background appears to influence disease severity, with non-Europeans facing higher hospitalization rates. In addition, access to high-quality samples and data is a critical issue for personalized and precision medicine, and it has become clear that the solution lies in biobanks. The creation of the Chilean COVID-19 Biorepository reported here addresses these gaps, representing the first nationwide multicentric Chilean initiative. It operates under rigorous biobanking standards and serves as one of South America’s largest COVID cohorts. A centralized harmonization strategy was chosen and included unified standard operating procedures, a sampling coding system, and biobanking staff training. Adults with confirmed SARS-CoV-2 infection provided broad informed consent. Samples were collected to preserve blood, plasma, buffy coat, and DNA. Quality controls included adherence to the standard preanalytical code, incident reporting, and DNA concentration and absorbance ratio 260/280 assessments. Detailed sociodemographic, health, medication, and preexisting condition data were gathered. In five months, 2262 participants were enrolled, pseudonymized, and sorted by disease severity. The average Amerindian ancestry considering all participant was 44.0% [SD 15.5%], and this value increased to 61.2% [SD 19.5%] among those who self-identified as Native South Americans. Notably, 279 participants self-identified with one of 12 ethnic groups. High compliance (>90%) in all assessed quality controls was achieved. Looking ahead, our team founded the COVID-19 Genomics Network (C19-GenoNet) focused on identifying genetic factors influencing SARS-CoV-2 outcomes. In conclusion, this bottom-up collaborative effort aims to promote the integration of Latin American populations into global genetic research and welcomes collaborations supporting this endeavor. Interested parties are invited to explore collaboration opportunities through our catalog, accessible online.
Marine picoplankton metagenomes and MaGs from eleven vertical profiles obtained by the Malaspina Expedition
(Nature Research, 2024) Sánchez, Pablo; Coutinho, Felipe H.; Sebastián, Marta; Pernice, Massimo C.; Rodríguez Martínez, Raquel; Salazar, Guillem; Cornejo Castillo, Francisco Miguel; Pesant, Stéphane; López-Alforja, Xabier; López-García, Ester María; Agustí, Susana; Gojobori, Takashi; Logares, Ramiro; Sala, Maria Montserrat; Vaqué, Dolors; Massana, Ramon; Duarte, Carlos M.; Acinas, Silvia G.; Gasol, Josep M.
The Ocean microbiome has a crucial role in Earth’s biogeochemical cycles. During the last decade, global cruises such as Tara Oceans and the Malaspina Expedition have expanded our understanding of the diversity and genetic repertoire of marine microbes. Nevertheless, there are still knowledge gaps regarding their diversity patterns throughout depth gradients ranging from the surface to the deep ocean. Here we present a dataset of 76 microbial metagenomes (MProfile) of the picoplankton size fraction (0.2–3.0 μm) collected in 11 vertical profiles covering contrasting ocean regions sampled during the Malaspina Expedition circumnavigation (7 depths, from surface to 4,000 m deep). The MProfile dataset produced 1.66 Tbp of raw DNA sequences from which we derived: 17.4 million genes clustered at 95% sequence similarity (M-GeneDB-VP), 2,672 metagenome-assembled genomes (MAGs) of Archaea and Bacteria (Malaspina-VP-MAGs), and over 100,000 viral genomic sequences. This dataset will be a valuable resource for exploring the functional and taxonomic connectivity between the photic and bathypelagic tropical and sub-tropical ocean, while increasing our general knowledge of the Ocean microbiome.
Contamination of urban soils in a historical mining town of northern Chile
(Springer Science and Business Media Deutschland GmbH, 2024) Garcia, D.; Tapia, J.; Vega, C.; Zúñiga, P.; Lavin, P.; Rojas, L.; Valdés, J.
In northern Chile, economic activities related to mining and thermoelectric energy have existed in the city of Tocopilla since the early 1900s and metal concentrations in soils have likely been altered by historic anthropogenic activities. To assess the concentrations of Cu, Zn, Pb, Ni, Co, and Cr in urban soils of Tocopilla, a total of 70 superficial (2 cm) and 70 deep (20 cm) soil samples were collected in 2014. Furthermore, to analyze concentration changes in soils over time, 18 superficial (5 cm) samples were collected in 2020–2021. A numerical evaluation (geoaccumulation index, and enrichment factor), principal component analysis, and spatial distribution approach were applied to infer geogenic and anthropogenic influence on the concentrations of these elements. The main conclusions of this research indicate that urban soils of Tocopilla contain geogenic Cu, Zn, Pb, Ni, Co and Cr. However, elevated concentrations of Cu, Zn, and Pb cannot be attributed to a geogenic origin alone, as a proportion of their enrichment is considered to be anthropogenically sourced. The contamination of anthropogenic elements has been found to be related to historic copper mining and thermoelectric energy production. Furthermore, when compared to other sites globally, median concentrations of Cu (945 mg/kg in 2014 and 823 mg/kg in 2020) and Zn (305 mg/ kg in 2014 and 196 mg/kg in 2020) in superficial urban soils are among the highest worldwide. Regarding 2020–2021 sampling, Zn and Pb concentrations have increased, while Cu, Cr, Co, and Ni have remained similar to the 2014 samples.
From a Brown to a blue economy in Chile
(ELSEVIER, 2024) Anbleyth Evans, Jeremy; Araos Leiva, Francisco; Gaymer, Carlos F.; Alvarez Abel, Ricardo R. ; Campos, Leonardo; Hidalgo, Carlos
The Chilean brown economy continues to expand, without specific definition of sustainable limits or how to transition to an ecologically balanced future. The article first reviews marine democracy across 42 cases of mining and coastal refinery projects, port developments, aquaculture, factory contamination, wind farms, coal and property development. In depth, an industrial fish factory cluster in Arica, a coastal zone impacted by mining in Cha˜naral, and fjord aquaculture in Puyuhapi. Using semi structured interviews, and participatory GIS focus groups, it shows the same issues repeat, and how a new participatory marine democratic system might transition the blue economy.
Differences in the adulteration degree and antimicrobial activity of chilean ulmo honey versus multifloral honey revealed by stable isotope analysis
(ELSEVIER, 2024) Pérez, Pablo; Lavín, Paris; Harrod, Chris; Echeveste, Pedro
Honey, valued for its nutritional and antimicrobial benefits, has experienced an increased production in recent decades. However, this rise has been accompanied by concerns of adulteration, often involving the fraudulent addition of sugars. Our study sought to compare the physicochemical and isotopic properties of various honeys available to Chilean consumers, assessing the extent of adulteration. Samples included honey produced from bees that fed on multiple flowers and those fed by ulmo flowers – an endemic species of South America that produces a high-quality, high-cost honey – and analyzed for antimicrobial activity against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. The analysis of ash content (%), moisture (%), pH and total phenolic content (mg GAE/100 g honey) found little obvious differences among honeys regardless of the feeding flowers (multifloral vs ulmo), type of purchase market (formal vs informal) or origin of the honeys (Central vs Southern Chile). However, the use of stable isotope analysis (δ 13 C and δ 15 N) of honey provided a powerful means to identify the degree of adulteration prior to the point of sale. Multifloral honeys purchased at informal markets were all adulterated, and ulmo honeys included both the least and most adulterated honeys. Regarding their antimicrobial activity, most multifloral honeys were less effective than ulmo honeys. Notably, while multifloral honey activity was independent of adulteration, the antimicrobial activity of ulmo honey was negatively affected by adulteration.
Why aquatic scientists should use sulfur stable isotope ratios (ẟ34S) more often
(ELSEVIER, 2024) Raoult, Vincent; Phillips, Alexandra A.; Nelson, James; Niella, Yuri; Skinner, Christina; Bell Tilcock, Miranda; Burke, Patrick J.; Szpak, Paul; James, W. Ryan; Harrod, Chris
Over the last few decades, measurements of light stable isotope ratios have been increasingly used to answer questions across physiology, biology, ecology, and archaeology. The vast majority analyse carbon (δ13C) and nitrogen (δ15N) stable isotopes as the ‘default’ isotopes, omitting sulfur (δ34S) due to time, cost, or perceived lack of benefits and instrumentation capabilities. Using just carbon and nitrogen isotopic ratios can produce results that are inconclusive, uncertain, or in the worst cases, even misleading, especially for scientists that are new to the use and interpretation of stable isotope data. Using sulfur isotope values more regularly has the potential to mitigate these issues, especially given recent advancements that have lowered measurement barriers. Here we provide a review documenting case studies with real-world data, re-analysing different biological topics (i.e. niche, physiology, diet, movement and bioarchaeology) with and without sulfur isotopes to highlight the various strengths of this stable isotope for various applications. We also include a preliminary meta-analysis of the trophic discrimination factor (TDF) for sulfur isotopes, which suggest small (mean 0.4 ± 1.7 ‰ SD) but taxa- dependent mean trophic discrimination. Each case study demonstrates how the exclusion of sulfur comes at the detriment of the results, often leading to very different outputs, or missing valuable discoveries entirely. Given that studies relying on carbon and nitrogen stable isotopes currently underpin most of our understanding of various ecological processes, this has concerning implications. Collectively, these examples strongly suggest that researchers planning to use carbon and nitrogen stable isotopes for their research should incorporate sulfur where possible, and that the new ‘default’ isotope systems for aquatic science should now be carbon, nitrogen, and sulfur.
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.
Protist communities of microbial mats from the extreme environments of five saline Andean lagoons at high altitudes in the Atacama Desert
(Frontiers Media SA, 2024) Acosta, Eduardo; Nitsche, Frank; Dorador, Cristina; Arndt, Hartmut
Introduction:Heterotrophic protists colonizing microbial mats have received little attention over the last few years, despite their importance in microbial food webs. A significant challenge originates from the fact that many protists remain uncultivable and their functions remain poorly understood.Methods:Metabarcoding studies of protists in microbial mats across high-altitude lagoons of different salinities (4.3–34 practical salinity units) were carried out to provide insights into their vertical stratification at the millimeter scale. DNA and cDNA were analyzed for selected stations.Results:Sequence variants classified as the amoeboid rhizarian Rhogostoma and the ciliate Euplotes were found to be common members of the heterotrophic protist communities. They were accompanied by diatoms and kinetoplastids.Correlation analyses point to the salinity of the water columnas a main driver influencing the structure of the protist communities at the five studied microbial mats. The active part of the protist communities was detected to be higher at lower salinities (<20 practical salinity units).Discussion:We found a restricted overlap of the protist community between the different microbial mats indicating the uniqueness of these different aquatic habitats. On the other hand, the dominating genotypes present in metabarcoding were similar and could be isolated and sequenced in comparative studies(Rhogostoma, Euplotes,Neobodo). Our results provide a snapshot of the unculturable protist diversity thriving the benthic zone of ive athalossohaline lagoons across the Andean plateau.
Whole-genome sequencing of a Janthinobacterium sp. isolatedfrom the Patagonian Desert
(American Society For Microbiology, 2024) Cavanaugh, Nicole T.; Kumar, Girish; Reverdy Pearson, Alicyn; Colbert, Julia; Riquelme, Carlos; Hudson, André O.; Chai, Yunrong; Godoy Carter, Veronica
Janthinobacterium is a genus of Gram-negative environmental bacteria that survive extreme conditions by forming biofilms and producing pigments. Janthinobacterium sp. LS2A, an extremophile isolated from soil in the Chilean Patagonia, contains seven known biosynthetic gene clusters, including the purple pigment violacein, which may aid in its survival in harsh environments.
Diet of Andean Leaf-Eared Mice (Phyllotis) Living atExtreme Elevations on Atacama Volcanoes: Insights FromMetagenomics, DNA Metabarcoding, and Stable Isotopes
(WILEY, 2024) Quezada Romegialli, Claudio; Quiroga Carmona, Marcial; D'Elía, Guillermo; Harrod, Chris ; Storz, Jay F.
On the flanks of > 6000 m Andean volcanoes that tower over the Atacama Desert, leaf-eared mice (Phyllotis vaccarum) live at extreme elevations that surpass known vegetation limits. The diet of these mice in these barren, hyperarid environments has been the subject of much speculation. According to the arthropod fallout hypothesis, sustenance is provided by windblown in-sects that accumulate in snowdrifts (“aolian deposits”). Mice may also feed on saxicolous lichen or forms of cryptic vegetation that have yet to be discovered at such high elevations. We tested hypotheses about the diet of mice living at extreme elevations on Atacama volcanoes by combining metagenomic and DNA metabarcoding analyses of gut contents with stable isotope analyses of mouse tissues. Genomic analyses of contents of the gastrointestinal tract of a live-captured mouse from the summit of VolcánLlullaillaco (6739 m) revealed an opportunistic but purely herbivorous diet, including lichens. Although we found no evidence of animal DNA in gut contents of the summit mouse, stable isotope data indicate that mice from elevations at or near vegetation limits (~5100 m) include a larger fraction of animal prey in their diet than mice from lower elevations. Some plant species detected in the gut contents of the summit mouse are known to exist at lower elevations at the base of the volcano and in the surrounding Altiplano, suggesting that they may occur at higher elevations beneath the snowpack or in other cryptic microhabitats.
Complete genome sequence of Cellulomonas sp. strain ATA003
(American Society For Microbiology, 2024) Bartholomäus, Alexander; Mitzscherling, Julia; Lipus, Daniel; Wagner, Dirk; Lavin, Paris ; Contreras, Roberto ; Oses, Rómulo
The Gram-positive, rod-shaped endophytic bacterium Cellulomonas sp.strain ATA003 was isolated from the endemic cactus Maihueniopsis domeykoensis seeds collected in the Coastal Atacama Desert, Chile. Here, we present a circular genome with a size of 4,084,881 bp and a GC content of 73.8% obtained by Nanopore sequencing.
Sulfate Nutrition Modulates the Oxidative Response against Short-Term Al3+-Toxicity Stress in Lolium perenne cv. Jumbo Shoot Tissues
(MDPI, 2024) Vera Villalobos, Hernan ; Lunario Delgado, Lizzeth ; S. Gálvez, Anita ; Román Silva, Domingo; Mercado Seguel, Ana; Wulff Zottele, Cristián
Al3+-toxicity in acidic soils is among the main abiotic stress factors that generate adverse effects in plant growth; in leaves, it affects several physiological parameters such as photosynthesis and ROS balance, leading to limited crop production. On the other hand, sulfur is a macronutrient that has a key role against oxidative stress and improves plant growth in acidic soils; however, the implication of sulfate nutritional status in the modulation of short-term Al3+-toxicity tolerance mechanisms in plant leaves are barely reported. This study is focused on the role of sulfate on the leaf response of an Al3-sensitive perennial ryegrass (Lolium perenne cv. Jumbo) after 48 h of exposure. Lolium perenne cv. Jumbo seeds were cultivated in hydroponic conditions with modified Taylor Foy solutions supplemented with 120, 240, and 360 μM sulfate in the presence or absence of Al3+-toxicity. The L. perenne cv. Jumbo leaves were collected after 48 h of Al3+-toxicity exposure and processed to evaluate the effects of sulfate on Al3+ toxicity, measuring total proteins, mineral uptake, photosynthesis modulation, and ROS defense mechanism activation. The plants exposed to Al3+-toxicity and cultivated with a 240 μM sulfate amendment showed a recovery of total proteins and Ca2+ and Mg2+ concentration levels and a reduction in TBARS, along with no changes in the chlorophyll A/B ratio, gene expression of proteins related to photosynthesis (Rubisco, ChlAbp, and Fered), or ROS defense mechanism (SOD, APX, GR, and CAT) as compared with their respective controls and the other sulfate conditions (120 and 360 μM). The present study demonstrates that adequate sulfate amendments have a key role in regulating the physiological response against the stress caused by Al3+ toxicity.
Epibiotic bacterial community composition varies during different developmental stages of Octopus mimus: Study of cultivable representatives and their secondary metabolite production
(Public Library of Science, 2024) Hengst, Martha B.; Trench, Stephanie; Alcayaga, Valezka; Sepulveda Muñoz, Cristian; Bórquez, Jorge; Simirgiotis, Mario; Valenzuela, Fernando; Lody, Mario; Kurte, Lenka; Pardo Esté, Coral
Marine microbial communities colonizing the skin of invertebrates constitute the primary barrier between host and environment, potentially exerting beneficial, neutral, or detrimental effects on host fitness. To evaluate the potential contribution of epibiotic bacteria to the survival of early developmental stages of Octopus mimus, bacterial isolates were obtained from eggs, paralarvae, and adults. Their enzymatic activities were determined, and antibacterial properties were assessed against common marine pathogens. The isolates belonged to the phyla Proteobacteria, Actinomycetota, Bacteroidota, and Bacillota, represented by 21 genera and 27 species. Specific taxa were associated with each developmental stage, with only three species shared among different stages: Bacillus pumilus, B. megaterium, and Shewanella algae, which also inhibited the growth of all assayed pathogens. Organic extracts from Bacillus megaterium M8-1 were obtained, and UHPLC-MS analysis detected seventeen putative compounds, including two phenolic acids, three indole derivatives, and twelve oxylipins. Our findings provide novel data on cultivable bacterial representatives isolated from Octopus mimus capable of synthesizing chemical compounds with bioactive properties. These results contribute to a better understanding of the role of microbial communities in the survival of this invertebrate species during critical early life stages.

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