CONICET | Buscador de Institutos y Recursos Humanos

Maize (Zea mays L.) is, after wheat, the second most important cereal crop in human and animal diets worldwide. In Argentina, maize is cultivated in the main maize growing region (Buenos Aires, Santa Fe and Cordoba provinces) and in the Northwest (NOA) region from Argentina. Several maize diseases are caused by Fusarium species, leading to significant yield losses and potential risk of mycotoxin contamination. Fusarium temperatum was isolated from maize harvested in the NOA region. The knowledge on the effect of environmental conditions on fungal growth and fungal production is important from the point of view of the toxicological risk due to the presence of this species in different agro-ecological regions. The aim of the present study was: -to determine the effect of interacting conditions of temperature (15, 25 and 30 ºC), aW (0.95, 0.98 and 0.995) and incubation time (7, 14, 21 and 28 days) on growth and mycotoxin production: fusaproliferin (FP), moniliformin (MON), beauvericin (BEA) and fumonisin B1 (FB1) by two strains of F. temperatum isolated from Argentinean maize (strains RCFT 903 and RCFT 912). The strains were grown on irradiated maize grains and growth rate (mm/day) was obtained by linear regression during the lineal phase of growth. Toxin production was determined by a multi-toxin method based on HPLC-MS/MS. Growth rates for both strains significantly increased (P<0,005) while rising aW and temperature. The optimal growth condition for both strains was 0.995 aW at 30 ºC. The mycotoxin production was dependant on aW and temperature but not on the strain. FUS and BEA showed maximum production at 0.98 aW and 25 ºC and FB1 at 0.98 aW and 15 ºC. MON production was optimal at 0.995 aW and 30 ºC. For these toxins, excluding MON, the results indicate that aW and temperature stresses may be important for toxin accumulation mainly in the field late-stage of maize colonization when grain aW decrease.

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