Examinando por Autor "Mosquera, S."

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    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.
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    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.