Examinando por Autor "Villegas Escobar, Valeska"
Mostrando 1 - 10 de 10
Resultados por página
Opciones de ordenación
Ítem Bioprospección de bacterias con actividad antibacteriana para el manejo de R. solanacearum a nivel de microcosmos(Universidad EAFIT, 2019) Valencia Vargas, Merlin Andrea; Sierra Zapata, Laura; Villegas Escobar, Valeska; Villegas Escobar, ValeskaÍtem Cloning and expression of the predicted α/β hydrolase enzyme from Variovorax sp. EA-ED0101(Universidad EAFIT, 2020) Carmona Berrío, David; Villegas Escobar, Valeska; Correa Álvarez, Javier; Correa Álvarez, Javier; Villegas Escobar, ValeskaÍtem Experimento de evolución adaptativa de laboratorio para la selección de microorganismos con potencial degradativo del polietileno tereftalato (PET)(Universidad EAFIT, 2021) Metaute Molina, Estefanía; Villegas Escobar, Valeska; Villegas Escobar, ValeskaÍtem Fengycin C produced by Bacillus subtilis EA-CB0015(American Chemical Society, 2014) Ceballos, Isabel; J. Mira, John; Argel, Luz Edith; Orduz Peralta, Sergio; Romero Tabarez, Magally; Villegas Escobar, Valeska; Centro de Investigaciones del Banano; Instituto de Biotecnología, Universidad Nacional de Colombia, Bogotá; Universidad Nacional de Colombia, Medellín; Universidad EAFIT. Departamento de Ciencias; Valeska Villegas Escobar ( vvilleg2@eafit.edu.co.); Ciencias Biológicas y Bioprocesos (CIBIOP)Bacillus subtilis EA-CB0015 was isolated from the phyllosphere of a banana plant and tested for its potential to produce bioactive compounds against Mycosphaerella fijiensis -- Using a dual plate culture technique the cell-free supernatant of B. subtilis EA-CB0015 produced inhibition values of 89 ± 1% -- The active compounds were purified by solid-phase extraction and HPLC, and their primary structures determined using mass spectrometry and amino acid analysis -- A new fengycin isoform, fengycin C, with the amino acid sequence Glu-Orn-Tyr-Thr-Glu-Val-Pro-Gln-Thr-Ile was isolated -- The peptidic moiety differs from fengycin B at position 9 and from fengycin A at positions 6 and 9 -- The β-hydroxy fatty acyl chain is connected to the N-terminal of the decapeptide and can be saturated or unsaturated, ranging from 14 to 18 carbons -- The C-terminal residue of the peptidic moiety is linked to the tyrosine residue at position 3, forming the branching point of the acyl peptide and the eight-membered cyclic lactoneÍtem ¿Hay vida en el suelo que no podemos ver?(2015) Abad Restrepo, Ana Cristina; Villegas Escobar, Valeska; Gonzáles Cotes, Ana María; Abad Restrepo, Ana Cristina; Villegas Escobar, Valeska; Gonzáles Cotes, Ana MaríaÍtem Lipopeptides from Bacillus sp. EA-CB0959: Active metabolites responsible for in vitro and in vivo control of Ralstonia solanacearum(Academic Press Inc., 2018-07-31) Villegas Escobar, Valeska; González-Jaramillo LM; Ramirez, Maria; MONCADA, RUTH NATALIA; Sierra Zapata, Laura; Orduz, Sergio; Romero, Magally; Universidad EAFIT. Departamento de Ciencias; Ciencias Biológicas y Bioprocesos (CIBIOP)Broadening the spectrum of action of microbial bioactive compounds is a priority nowadays. From a collection of 1493 aerobic endospore forming bacteria, 3.1% (47) inhibited Serratia marcescens and were highly active against R. solanacearum. Thirty-six of these strains were identified as part of the ‘Operational Group B. amyloliquefaciens’ denoting the potential of strains from these species to produce antibacterial substances. Specifically, the strain Bacillus sp. EA-CB0959 was selected for further trials. Three families of lipopeptides: surfactins, iturins and fengycins were found as the active compounds produced by this strain. The highest bioactivity, produced by fengycins, had a minimal inhibitory concentration of 32 µg/mL. Treating greenhouse banana plants with a mixed fraction of lipopeptides reduced by 35% the incidence of Moko disease caused by R. solanacearum. Here we provide first time evidence of in vitro antibacterial activity of purified fengycins and in vivo activity of mixed lipopetides against Moko disease in banana plants. © 2018 Elsevier Inc.Ítem Multiple response optimization of Bacillus subtilis EA-CB0015 culture and identification of antifungal metabolites(Biocatalysis and Agricultural Biotechnology, 2014) Ordúz, Sergio; Mosquera, Sandra; González Jaramillo, Lina María; Villegas Escobar, Valeska; Escuela de Biociencias; Centro de Investigaciones del Banano; Universidad EAFIT. Departamento de Ciencias; Valeska Villegas-Escobar (vvilleg2@eafit.edu.co); Ciencias Biológicas y Bioprocesos (CIBIOP)The low yields of biomass and antimicrobial metabolites obtained in fermentation processes are limiting factors for implementing biological control agents in the field -- In this context, optimization of the culture medium for the biological control agent Bacillus subtilis EA-CB0015 was conducted in submerged culture to maximize the biomass production and antifungal activity -- Additionally, the active metabolites against the phytopathogen Mycosphaerella fijiensis produced under optimized conditions were identified -- Carbon and nitrogen constituents of the culture medium were optimized using a 22 factorial design with central point followed by a multiple response optimization coupled to the desirability function approach -- The optimized medium (33.4 g/L of glucose and 32.5 g/L of yeast extract), showed significant increases in both, cell density by 3.6 folds (13.271.0 g/L) and antifungal activity by 1.2 folds (77.770.3% inhibition) -- To gain insight into the type of active compounds, they were purified and identified by mass spectrometry (MS) -- The MS analysis revealed the presence of three families of lipopeptides: surfactin, fengycin and iturin -- The high antifungal activity was associated with the novel fengycin C and with iturin -- A which were partially growth-associated with a maximum concentration of 781.4 and 355.4 mg/L at 36 h of growth, respectively -- These results indicate the potential of B. subtilis EA-CB0015 to produce high concentrations of biomass and lipopeptides that can be exploited for biotechnological applicationÍtem Production evaluation of Lentinula edodes Pegler fungi in synthetic logs based on agricultural wastes(Universidad EAFIT, 2007-12-12) Villegas Escobar, Valeska; Milena Pérez, Ana; Arredondo, Clara; Universidad EAFITÍtem Reviewing microbial behaviors in ecosystems leading to a natural quorum quenching occurrence(INST TECNOLOGIA PARANA, 2017-01-01) Sierra Zapata, Laura; Romero Tabarez, Magally; Correa Alvarez, Javier; Villegas Escobar, Valeska; Universidad EAFIT. Departamento de Ciencias; Biodiversidad, Evolución y ConservaciónQuorum sensing is considered one of the most important discoveries in cell-to-cell communication. Although revealed in Bacteria, it has been identified as well as a mechanism present in the other two domains, Eukaryota and Archaea. This phenomenon consists mainly of an exchange and sensing of "words" produced by each cell: chemical signals known as autoinducers. The process takes places at high cell densities and confined environments, triggering the expression of specific genes that manifest in a determined phenotype. Quorum sensing has a fundamental importance in the organisms' fitness in natural ecosystems since it activates many of the traits needed by cells to survive under specific conditions, and thus a wide variety of chemical signals, which are detailed throughout the review, have evolved in response to the needs of an organism in the ecosystem it inhabits. As a counterpart, derived from the natural occurrence of quorum sensing, comes it's antagonistic process named quorum quenching. Acting in the exact opposite way, quorum quenching interferes or degrades the autoinducers confusing and stopping communication, hence affecting transcriptional regulation and expression of a specific phenotype. The main reasons for stopping this mechanism go from fading their own signals when perceiving scarce nutrients conditions, to degrading competitors' signals to take advantage in the ecosystem. Some of the most studied purposes and means known up to date to be used by cells for making quorum quenching in their ecosystems is what will be discussed along this review, offering information for future works on quorum quencher molecules bioprospection.Ítem Reviewing microbial behaviors in ecosystems leading to a natural quorum quenching occurrence(INST TECNOLOGIA PARANA, 2017-01-01) Sierra Zapata, Laura; Romero Tabarez, Magally; Correa Alvarez, Javier; Villegas Escobar, Valeska; Universidad EAFIT. Departamento de Ciencias; Ciencias Biológicas y Bioprocesos (CIBIOP)Quorum sensing is considered one of the most important discoveries in cell-to-cell communication. Although revealed in Bacteria, it has been identified as well as a mechanism present in the other two domains, Eukaryota and Archaea. This phenomenon consists mainly of an exchange and sensing of "words" produced by each cell: chemical signals known as autoinducers. The process takes places at high cell densities and confined environments, triggering the expression of specific genes that manifest in a determined phenotype. Quorum sensing has a fundamental importance in the organisms' fitness in natural ecosystems since it activates many of the traits needed by cells to survive under specific conditions, and thus a wide variety of chemical signals, which are detailed throughout the review, have evolved in response to the needs of an organism in the ecosystem it inhabits. As a counterpart, derived from the natural occurrence of quorum sensing, comes it's antagonistic process named quorum quenching. Acting in the exact opposite way, quorum quenching interferes or degrades the autoinducers confusing and stopping communication, hence affecting transcriptional regulation and expression of a specific phenotype. The main reasons for stopping this mechanism go from fading their own signals when perceiving scarce nutrients conditions, to degrading competitors' signals to take advantage in the ecosystem. Some of the most studied purposes and means known up to date to be used by cells for making quorum quenching in their ecosystems is what will be discussed along this review, offering information for future works on quorum quencher molecules bioprospection.