RESUMO

Fungal secondary metabolites with antimicrobial properties are used for biological pest control. Their production is influenced by several factors as environment, host, and culture conditions. In the present work, the secondary metabolites from fermented extracts of Beauveria bassiana PQ2 were tested as antifungal agents against Gibberella moniliformis LIA. The L18 (21 × 37) orthogonal array from Taguchi methodology was used to assess 8 parameters (pH, agitation, sucrose, yeast extract, KH2PO4, MgSO4, NH4NO3, and CaCl2) in B. bassiana PQ2 submerged fermentation. The ability of the fermented extracts to slow down the growth rate of G. moniliformis LIA was evaluated. The results from 18 trials were analyzed by Statistica 7 software by evaluating the signal-to-noise ratio (S/N) to find the lower-the-better condition. Optimal culture conditions were pH, 5; agitation, 250 rpm; sucrose, 37.5 g/L-1; yeast extract, 10 g/L-1; KH2PO4, 0.8 g/L-1; MgSO4, 1.2 g/L-1; NH4NO3, 0.1 g/L-1; and CaCl2, 0.4 g/L-1, being the agitation at the highest level the most significant factor. The optimal conditions were validated in a sparged bottle bioreactor resulting in a higher S/N value (12.48) compared to the estimate. The extract obtained has the capacity to inhibit the germination of G. moniliformis spores at 24 h. HPLC-ESI-MS2 allowed to identify the water-soluble red pigment as oosporein (m/z 304.9). The secondary metabolites from B. bassiana PQ2 are a suitable alternative to control the growth and sporulation of G. moniliformis.

Assuntos

Beauveria , Fusarium , Reatores Biológicos , Controle Biológico de Vetores/métodos , Esporos Fúngicos

RESUMO

Physicochemical, antifungal and antioxidant properties of a pectin - aloe mucilage - candelilla wax - Larrea tridentata polyphenols based bioactive film were evaluated. Antifungal capacity was analyzed against Botrytis cinerea, Colletotrichum gloeosporioides, Fusarium oxysporum and Alternaria alternata. The main antioxidants in Larrea tridentata polyphenols were identified by HPLC-MS. Water vapor permeability (WVP) was measured in the film. Antioxidant capacities for ABTS· +, DPPH·, lipid oxidation inhibition (LOI) and ferric reducing antioxidant power (FRAP) (97, 92, and 57 %, 0.73 mM Fe, respectively) were evaluated. It was possible to determine the MIC50 for the fungi evaluated at concentrations of 558-612 ppm of polyphenols. Antioxidants identified were nordihydroguaiaretic acid (NDGA), Quercetin, and Kaenpherol. Treatment with 1.1 % of pectin, 0.16 % candelilla wax, 0.3 % glycerol, 5 % AM and 4 % extract of polyphenols showed values of thickness and WVP suitable to be applied on model fruits.