Examinando por Materia "Mycosphaerella fijiensis"
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Ítem Antimycotic activity of fengycin C biosurfactant and its interaction with phosphatidylcholine model membranes(ELSEVIER SCIENCE BV, 2017-08-01) González-Jaramillo LM; Aranda FJ; Teruel JA; Villegas-Escobar V; Ortiz A; Universidad EAFIT. Departamento de Ciencias; Ciencias Biológicas y Bioprocesos (CIBIOP)Lipopeptide biosurfactants constitute one of the most promising groups of compounds for the treatment and prevention of fungal diseases in plants. Bacillus subtilis strain EA-CB0015 produces iturin A, fengycin C and surfactin and it has been proven useful for the treatment of black Sigatoka disease in banana plants, an important pathology caused by the fungus Mycosphaerella fijiensis (Morelet). We have found that B. subtilis EA-CB0015 cell free supernatants and purified fractions inhibit M. fijiensis cellular growth. The effect of the purified lipopeptides mentioned above on fungal growth has been also evaluated, observing that iturin A and fengycin C inhibit mycelial growth and ascospore germination, whereas surfactin is not effective. On the hypothesis that the antifungal action of the lipopeptides is associated to their incorporation into biological membranes, ultimately leading to membrane permeabilization, a detailed biophysical study on the interaction of a new isoform of fengycin C with model dipalmitoyphosphatidylcholine (DPPC) membranes has been carried out. Differential scanning calorimetry shows that fengycin C alters the thermotropic phase transitions of DPPC, and is laterally segregated in the fluid bilayer forming domains. Fluorescent probe polarization measurements show that fengycin C does not affect the hydrophobic interior of the membrane. This latter perturbation is concomitant with a strong dehydration of the polar region of DPPC, as shown by FTIR. Fengycin-rich domains, where the surrounding DPPC molecules are highly dehydrated, may well constitute sites of membrane permeabilization leading to a leaky target membrane. These results are a solid support to explain the membrane perturbing action of fengycin, which has been related to its antifungal activity. (C) 2017 Elsevier B.V. All rights reserved.Ítem Efecto de rizobacterias aeróbicas formadoras de endospora sobre Mycosphaerella fijiensis(Universidad EAFIT, 2009-10-15) Estrada Arango, Natalia; Rivera Rodríguez, Diana Marcela; Posada Uribe, Luisa Fernanda; Mosquera López, SandraÍtem Effective control of black Sigatoka disease using a microbial fungicide based on Bacillus subtilis EA-CB0015 culture(Academic Press Inc., 2015-08-01) Gutierrez-Monsalve, J.A.; Mosquera, S.; González-Jaramillo, L.M.; Mira, J.J.; Villegas-Escobar, V.; Universidad EAFIT. Departamento de Ciencias; Ciencias Biológicas y Bioprocesos (CIBIOP)Black Sigatoka disease caused by the fungus Mycosphaerella fijiensis Morelet is the most devastating disease of bananas worldwide. Its management is reliant on protectant and systemic fungicides despite their environmental concerns. This study evaluated the effect of a microbial fungicide (MF) based on Bacillus subtilis EA-CB0015 and its metabolites for the control of black Sigatoka disease on banana plants in greenhouse and field conditions. The MF applied at 1.5. L/ha and 3.0. L/ha provided control of the disease comparable to the protectant fungicide chlorothalonil in greenhouse. In the field, the MF applied in solution with water at 0.15. L/ha and 1.5. L/ha every 11. days during 10. weeks reduced black Sigatoka disease severity in 20.2% and 28.1% respectively; reductions comparable to those obtained with the protectant fungicides chlorothalonil (1.5. L/ha) and mancozeb (3.8. L/ha). The MF incorporated into different programs with systemic fungicides reduced disease level up to 42.9% with no significant differences with the conventional program. To determine which component of the MF is responsible for the activity against M. fijiensis, greenhouse and in vitro tests were set up to evaluate individually the spores, vegetative cells and secondary metabolites of B. subtilis EA-CB0015. All components reduced the severity of the disease and the germination of ascospores. For both trials the activity of the metabolites was higher and comparable to the activity obtained with the MF, indicating that the efficacy of the MF depends mainly on the metabolites and in lesser extent to B. subtilis EA-CB0015 cells. © 2015 Elsevier Inc.Ítem Fengycin C produced by Bacillus subtilis EA-CB0015.(AMER CHEMICAL SOC, 2013-04-26) Villegas-Escobar, Valeska; Ceballos, Isabel; Mira, John J.; Edith Argel, Luz; Orduz Peralta, Sergio; Romero-Tabarez, Magally; Universidad EAFIT. Departamento de Ciencias; 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 beta-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 lactone.Ítem Multiple response optimization of Bacillus subtilis EA-CB0015 culture and identification of antifungal metabolites(Elsevier Ltd, 2014-01-01) Mosquera, S.; González-Jaramillo, L.M.; Orduz, S.; Villegas-Escobar, V.; Universidad EAFIT. Departamento de Ciencias; 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 (33.4g/L of glucose and 32.5g/L of yeast extract), showed significant increases in both, cell density by 3.6 folds (13.2±1.0g/L) and antifungal activity by 1.2 folds (77.7±0.3% 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 355.4mg/L at 36h 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 application. © 2014 Elsevier Ltd.