INVESTIGADORES
CHULZE Sofia Noemi
congresos y reuniones científicas
Título:
Potential Inoculum source for Aspergillus section Nigri in vineyards from Argentina
Autor/es:
PONSONE, L; COMBINA, M; DALCERO, A.; CHULZE, S
Lugar:
Villa Carlos Paz, Cordoba
Reunión:
Congreso; Conferencia Advances in research on toxicogenic fungi and mycotoxins in South America ensuring food and feed safety in a mycoglobe context; 2006
Institución organizadora:
Comision Europea-UNRC
Resumen:
Grapes can be often invaded before harvest by Aspergillus section Nigri. Weeds and soil could be one potential inoculum sources for these fungi. The aims of the present study were -to isolate and identify the Aspergillus species, potentially ochratoxigenic isolated from weeds and soil through different stages of grapes development -to determinate the ochratoxigenic ability of the isolated strains. Fifty weeds and soil samples were collected at setting, one month after setting, early veraison and harvest from four vineyards located at 85 Km eastern Mendoza, 33º 16´ South Latitude 68º 09´ West Longitude. The vineyards chosen were representative of the grape-growing area as regards grape variety and farming methods. Isolation and enumeration of fungal propagules were done on Dichloran Rose Bengal Chloramphenicol Agar (DRBC) and Dichloran 18% Glycerol Agar (DG18) using the surface-spread method. Identification of the Aspergillus species was done according to Pitt and Hocking (1997) and Klich (2002). The ability to produce ochratoxin A (OTA) was done on YES medium (2% yeast extract, 15% sucrose). The cultures were incubated at 30ºC ± 1ºC for 10 days in darkness. OTA was detected and quantify by HPLC. From weeds samples the most frequent genus isolated was Cladosporium, follow by Aspergillus, Fusarium, Penicillium, Alternaria and Paecilomyces in minor percentage. The prevalent potentially ochratoxigenic species isolated from weeds were A. niger and A. awamori in all growth stages. A japonicus, A aculeatus, and A foetidus were also present, although the distribution varied according to the growth stage, the grape variety or the cropping system. From soil samples the ochratoxigenic species have similar distribution, however the level was higher than in weeds samples. From 110 black Aspergilli strains, isolated from weeds 15.5% were OTA producers with levels ranging from 1.2 to 45.9 ng/mL. While among 184 black aspergilli strains isolated from soil 34% were OTA producers with levels ranging from 1.7 to 42.3 ng/mL. The incidence of toxigenics species of Aspergillus section Nigri point weeds and soil as one possible source of inoculum of black aspergilli in the vineyard.     Soil and weeds are important inoculum sources of ochratoxigenic species    through      the        different stages of grapes maturation.