Browsing by Author "Vicuña, Rafael"
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- ItemAlma Humana y Evolución(1999) Vicuña, Rafael
- ItemAssesment of Various Commercial Enzymes in the Bleaching of Radiata Pine Kraft Pulps(1995) Vicuña, Rafael
- ItemBiotechnology in Chile(1994) Vicuña, Rafael
- ItemBiotecnología: mercados y bioética(2008) Vicuña, Rafael
- ItemBleaching of Eucalyptus Kraft Pulp With Commercial Xylanases(1997) Vicuña, Rafael
- ItemBleaching of Radiata Pine Kraft Pulp With the Enzone Process(1995) Vicuña, Rafael
- ItemCatabolism of 1,2 Diarylethane Lignin Model Compounds by Two Brown-Rot Fungi(1990) Agosin T., Eduardo; Vicuña, Rafael
- ItemEl Debate de los Transgénicos: Una Perspectiva Desde la Ciencia(2001) Arce Johnson, Jorge Patricio; Vicuña, Rafael
- ItemEffect ofStreptomyces viridosporus T7A on kraft lignin(1990) Seelenfreund, Daniela; Vicuña, RafaelThe ability of the lignino-cellulolytic actinomyceteStreptomyces viridosporus T7A to attack purified fractions of kraft lignin was examined. In the presence of 0.3% yeast extract, high-molecular weight kraft lignin (MW>3000, ether-insoluble fraction) does not affect growth of this microorganism significantly, whereas low-molecular weight kraft lignin (MW<3000, ether-soluble fraction) inhibits its development. Accordingly, average molecular weight of the ether-insoluble fraction after bacterial growth remained unaltered, as measured by Sephadex G-50 gel permeation chromatography. Slight modifications were detected by high performance liquid chromatography in the ether-soluble fraction after incubation with the microorganism.S. viridosporus T7A partially decolorized Remazol Brilliant Blue R during growth on wheat lignocellulose. However, decolorization of either fraction of kraft lignin was not observed. These results suggest that the filamentous bacteriumS. viridosporus T7A is not suitable for pulp mill effluent treatment.
- ItemGenomic Features for Desiccation Tolerance and Sugar Biosynthesis in the Extremophile Gloeocapsopsis sp. UTEX B3054(2019) Urrejola, Catalina; Alcorta Loyola, Jaime Andrés; Salas, Loreto; Vásquez, Mónica; Polz, Martin; Vicuña, Rafael; Díez, BeatrizFor tolerating extreme desiccation, cyanobacteria are known to produce both compatible solutes at intracellular level and a copious amount of exopolysaccharides as a protective coat. However, these molecules make cyanobacterial cells refractory to a broad spectrum of cell disruption methods, hindering genome sequencing, and molecular studies. In fact, few genomes are already available from cyanobacteria from extremely desiccated environments such as deserts. In this work, we report the 5.4 Mbp draft genome (with 100% of completeness in 105 contigs) of Gloeocapsopsis sp. UTEX B3054 (subsection I; Order Chroococcales), a cultivable sugar-rich and hardly breakable hypolithic cyanobacterium from the Atacama Desert. Our in silico analyses focused on genomic features related to sugar-biosynthesis and adaptation to dryness. Among other findings, screening of Gloeocapsopsis genome revealed a unique genetic potential related to the biosynthesis and regulation of compatible solutes and polysaccharides. For instance, our findings showed for the first time a novel genomic arrangement exclusive of Chroococcaceae cyanobacteria associated with the recycling of trehalose, a compatible solute involved in desiccation tolerance. Additionally, we performed a comparative genome survey and analyses to entirely predict the highly diverse pool of glycosyltransferases enzymes, key players in polysaccharide biosynthesis and the formation of a protective coat to dryness. We expect that this work will set the fundamental genomic framework for further research on microbial tolerance to desiccation and to a wide range of other extreme environmental conditions. The study of microorganisms like Gloeocapsopsis sp. UTEX B3054 will contribute to expand our limited understanding regarding water optimization and molecular mechanisms allowing extremophiles to thrive in xeric environments such as the Atacama Desert.
- ItemGloeocapsopsis AAB1, a Cyanobacterium highly tolerant to desiccation isolated from the Atacama desert.(2013) Azúa Bustos, Armando; Vicuña, Rafael; Pontificia Universidad Católica de Chile. Facultad de Ciencias BiológicasEl acabado estudio de los microorganismos que han evolucionado en el Desierto de Atacama, el más seco y antiguo del mundo, permitirían entender el rol clave del agua para la vida en general. Para aproximarse a este fin, primero caracterizamos el microambiente que permite la colonización de cuarzos de la Cordillera de la Costa de este desierto por microorganismos hipolíticos. A continuación describimos la composición de la biodiversidad microbiana de estos biofilms, aislando posteriormente una cepa de cianobacteria desde éstos. Basados en análisis morfológicos y filogenéticos, el aislado (AAB1) fue clasificado como un nuevo miembro del género Gloeocapsopsis. Los cambios mostrados por células del aislado AAB1 en condiciones de desecación indicaron que éste es altamente tolerante a esta condición de estrés. Adicionalmente, nuestros resultados indican que el aislado sintetiza sacarosa y trehalosa en respuesta a la desecación. Posteriormente identificamos los dos genes candidatos involucrados en la síntesis de sacarosa (la sacarosa-6-fosfato sintetasa y la sacarosa-6-fosfato fosfatasa).
- ItemGrowth of Pinus Radiata in Soil Containing Solid Waste From the Kraft Pulp Industry(2000) Jordán Zimmerman, Miguel; Vicuña, Rafael; González Ojeda, Bernardo; Bronfman A., Miguel L.; Jordán Zimmerman, Miguel; Vicuña, Rafael; González Ojeda, Bernardo; Bronfman A., Miguel L.; Jordán Zimmerman, Miguel; Vicuña, Rafael; González Ojeda, Bernardo; Bronfman A., Miguel L.
- ItemIsolation of UVC-Tolerant Bacteria from the Hyperarid Atacama Desert, Chile(2013) Paulino-Lima, Iván Gláucio; Azúa Bustos, Armando.; Vicuña, Rafael; Salas Díaz, Loreto Alejandra Chantal.
- ItemLigninolysis(2000) Vicuña, Rafael
- ItemLoss of Filamentous Multicellularity in Cyanobacteria: the Extremophile Gloeocapsopsis sp. Strain UTEX B3054 Retained Multicellular Features at the Genomic and Behavioral Levels(2020) Urrejola Santa Maria, Catalina; Dassow, Peter von; van den Engh, G.; Salas, L.; Mullineaux, C. W.; Vicuña, Rafael; Sánchez-Baracaldo, P.
- ItemMicrobial biodiversity: A new voyage of discovery(2006) Vicuña, Rafael
- ItemEl origen de la vida en la tierra: ¿acción de la naturaleza y/o intervención divina?(2014) Vicuña, Rafael