Gutiérrez Moraga, Ana

Bacteriocins are antimicrobial peptides of ribosomal synthesis secreted by bacteria. Among these, nisin stands out, which has potential uses in antibiotic therapies, as a food bio preservative and probiotics. Nisin has also been reported to have cytotoxicity on neoplastic cell lines, but there is little information on its effect on blood tumor cells. Due to the potential use that nisin presents, it is relevant to determine the toxicity it presents on tumor cell lines of the blood type. For this, hemolytic activity tests were carried out on human erythrocytes and toxicity on human peripheral blood mononuclear cells, determining that nisin does not have a toxic effect on this type of normal human blood cells. Cytotoxicity tests were also carried out with tumor cell lines (K562 and U937), to determine dose, exposure time and selectivity in the toxic effect of nisin on human tumor cells. These tests show that nisin shows cytotoxic activity on K562 and U937 cell lines at 72 h of exposure, at a concentration of 40 µg / mL, which corresponds to 100 times the minimum inhibitory concentration (MIC) used for its action on bacteria. When comparing the effect of nisin on human peripheral blood mononuclear cells with lymphoid and myeloid tumor lines (K562 and U937 respectively), a selective effect of nisin on blood tumor cells is observed. © 2022, Universidad de la Frontera. All rights reserved.

Cancer is the second leading cause of death in the world and colorectal cancer is the only cancer that has shown a sustained increase in mortality in the last decade. In the search for new chemotherapeutic agents against cancer, extremophilic microorganisms have shown to be a potential source to obtain molecules of natural origin and with selective cytotoxic action towards cancer cells. In this work we analyzed the ability of a collection of Antarctic soil bacteria, isolated on Collins Glacier from the rhizosphere of Deschampsia antarctica Desv plant, to secrete molecules capable of inhibiting cell proliferation of a colorectal cancer tumor line. Our results demonstrated that culture supernatants from the Antarctic bacteria K2I17 and MI12 decreased the viability of LoVo cells, a colorectal adenocarcinoma cell line. Phenotypic and genotypic characterization of the Antarctic bacteria showed that they were taxonomically related and nucleotide identity analysis based on the 16S rRNA gene sequence identified the bacterium K2I17 as a species belonging to the genus Bacillus. © 2023, Universidad de la Frontera. All rights reserved.

Antarctic soils are considered young soils; therefore, the microbiota associated with Antarctic vascular plants play a critical role in their productivity. In this research, we compared the microbiota from three different soil conditions using a 16S rRNA and internal transcribed spacer rRNA gene amplicon approach for bacterial and fungal communities.

Tuberculosis (TB) is one of the leading causes of human deaths worldwide caused by infectious diseases. TB infection by Mycobacterium tuberculosis can occur in the lungs, causing pulmonary tuberculosis (PTB), or in any other organ of the body, resulting in extrapulmonary tuberculosis (EPTB). There is no consensus on the genetic determinants of this pathogen that may contribute to EPTB. In this study, we constructed the M. tuberculosis pangenome and used it as a tool to seek genomic signatures associated with the clinical presentation of TB based on its accessory genome differences. The analysis carried out in the present study includes the raw reads of 490 M. tuberculosis genomes (PTB n = 245, EPTB n = 245) retrieved from public databases that were assembled, as well as ten genomes from Mexican strains (PTB n = 5, EPTB n = 5) that were sequenced and assembled. All genomes were annotated and then used to construct the pangenome with Roary and Panaroo. The pangenome obtained using Roary consisted of 2231 core genes and 3729 accessory genes. On the other hand, the pangenome resulting from Panaroo consisted of 2130 core genes and 5598 accessory genes. Associations between the distribution of accessory genes and the PTB/EPTB phenotypes were examined using the Scoary and Pyseer tools. Both tools found a significant association between the hspR, plcD, Rv2550c, pe_pgrs5, pe_pgrs25, and pe_pgrs57 genes and the PTB genotype. In contrast, the deletion of the aceA, esxR, plcA, and ppe50 genes was significantly associated with the EPTB phenotype. Rv1759c and Rv3740 were found to be associated with the PTB phenotype according to Scoary; however, these associations were not observed when using Pyseer. The robustness of the constructed pangenome and the gene–phenotype associations is supported by several factors, including the analysis of a large number of genomes, the inclusion of the same number of PTB/EPTB genomes, and the reproducibility of results thanks to the different bioinformatic tools used. Such characteristics surpass most of previous M. tuberculosis pangenomes. Thus, it can be inferred that the deletion of these genes can lead to changes in the processes involved in stress response and fatty acid metabolism, conferring phenotypic advantages associated with pulmonary or extrapulmonary presentation of TB. This study represents the first attempt to use the pangenome to seek gene–phenotype associations in M. tuberculosis. © 2023 by the authors.

Low fermentation temperatures are usually employed to obtain high-quality wines. This is especially interesting for white wine production since it prevents the loss of volatile compounds and a browning appearance; however, available fermentative yeasts do not usually tolerate low temperatures. Therefore, an interesting place to find new yeasts with cryotolerance is the Antarctic continent. From soil samples collected in Antarctica, 125 yeasts were isolated, of which 25 exhibited fermentative activity at 10 °C. After a fingerprinting assay, we classified the candidates into nine isotypes and sequenced internal transcribed spacer regions for their identification. These yeasts were identified as part of the Mrakia genus. Sugar and alcohol tolerance tests showed that some of these Antarctic soil yeasts were able to grow up to 9% alcohol, and 25% sugar was reached; however, they exhibited longer latency periods compared to the control Saccharomyces cerevisiae. The optimal growing temperature for the isolated Antarctic yeasts was between 10 °C and 15 °C. A comprehensive analysis of the results obtained showed that the isolates 10M3-1, 4M3-6, and 4B1-35 could be good candidates for fermentation purposes due to their alcohol, sugar tolerance, and growth features. Our results prove that it is possible to isolate fermentative yeasts from Antarctic soil with promising characteristics for their potential use in the wine production industry. © 2023 by the authors.

El compromiso con la investigación científica, ese ejercicio de indagación rigurosa y de diálogo crítico con el mundo, es uno de los rasgos que distingue a una universidad que asume, con pleno sentido, su papel en la formación de sus estudiantes. En el décimo aniversario del Programa de Iniciación Científica, es preciso reconocer cómo este ha contribuido a transformar el entorno universitario, dotando a los estudiantes de una mirada reflexiva y una capacidad crítica indispensable para el tiempo que vivimos. Este programa no solo es una puerta hacia la ciencia, sino también hacia el mundo real, donde los conocimientos adquiridos en el aula encuentran el eco y la validación de los problemas contemporáneos. A lo largo de estos años, los estudiantes han desarrollado proyectos que abordan temas de la más variada índole: desde el desafío que plantea la transición hacia energías limpias hasta los dilemas éticos y prácticos que surgen en la inteligencia artificial o la salud pública. En cada uno de estos esfuerzos, se percibe el compromiso con su entorno y una clara conciencia de que la ciencia, en última instancia, debe estar al servicio de la sociedad. La valorización de la investigación universitaria representa, en este contexto, una verdadera expansión de los horizontes estudiantiles. Aquí, la investigación aplicada no es un mero ejercicio técnico, sino un acto de responsabilidad social que alienta a los estudiantes a ver la realidad con una perspectiva crítica, a cuestionar sus premisas y, cuando es necesario, a proponer soluciones innovadoras y factibles. En cada proyecto los estudiantes encuentran un desafío que va más allá de la teoría y se adentra en los complejos matices de lo concreto; y en cada uno, la universidad renueva su compromiso de ser un espacio en el que el saber no solo se construye, sino que también se transforma y se aplica. Desde la Vicerrectoría de Investigación reafirmamos nuestro propósito de cultivar este espacio en el que los estudiantes puedan, a través de la investigación, desarrollar una comprensión profunda de su entorno, un juicio crítico frente a los problemas de su tiempo y una capacidad creativa para enfrentarlos. Este Programa de Iniciación Científica es, en ese sentido, no solo un punto de partida, sino un pilar de la formación de profesionales comprometidos, críticos y responsables.

Deschampsia antarctica Desv. (Poaceae) is one of the two vascular plants that have colonized the Antarctic Peninsula, which is usually exposed to extreme environmental conditions. To support these conditions, the plant carries out modifications in its morphology and metabolism, such as modifications to the cell wall. Thus, we performed a comparative study of the changes in the physiological properties of the cell-wall-associated polysaccharide contents of aerial and root tissues of the D. antarctica via thermogravimetric analysis (TGA) combined with a computational approach. The result showed that the thermal stability was lower in aerial tissues with respect to the root samples, while the DTG curve describes four maximum peaks of degradation, which occurred between 282 and 358◦C. The carbohydrate polymers present in the cell wall have been depolymerized showing mainly cellulose and hemicellulose fragments. Additionally, a differentially expressed sequence encoding for an expansin-like (DaEXLA2), which is characterized by possessing cell wall remodeling function, was found in D. antarctica. To gain deep insight into a probable mechanism of action of the expansin protein identified, a comparative model of the structure was carried out. DaEXLA2 protein model displayed two domains with an open groove in the center. Finally, using a cell wall polymer component as a ligand, the protein–ligand interaction was evaluated by molecular dynamic (MD) simulation. The MD simulations showed that DaEXLA2 could interact with cellulose and XXXGXXXG polymers. Finally, the cell wall component description provides the basis for a model for understanding the changes in the cell wall polymers in response to extreme environmental conditions. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.