In Uruguay, Fusarium graminearum is the most common species that infects wheat and is responsible for Fusarium head blight (FHB) and contamination of grain with deoxynivalenol (DON). The aim of this work was to select bacterial endophytes isolated from wheat grain to evaluate their antagonistic ability against F. graminearum and DON production in vitro and under field conditions. Four strains identified as Bacillus megaterium (BM1) and Bacillus subtilis (BS43, BSM0 y BSM2) significantly reduced fungal growth and spore germination of F. graminearum. This antagonist activity remained unchanged after the bacterial cultures were heat treated. Under field conditions, treatments with antagonist BM1 was the most effective, reducing the FHB incidence and severity by 93 and 54 %, respectively, and the production of DON by 89.3 %.

Silage, one of the most important feed sources for cattle, is vulnerable to contamination by spoilage moulds and mycotoxins because ensilage materials are excellent substrates for fungal growth. The aim of this study was to identify the mycobiota of sorghum silages, to determine the presence of aflatoxins and fumonisins, and to correlate these results with physical parameters of the silage. A total of 275 samples of sorghum were collected from dairy farms in the south-west region of Uruguay were silage practices are developed. The presence of fungi was observed in all of the sorghum samples with values varying from 0.2 × 10 to 4085 × 10 UFC g. Significant difference were detected in the total number of fungi during the storage period; at six months there is a high risk of fungal spoilage. The most frequent genera isolated from sorghum samples were Penicillium (70%), Aspergillus (65%), Absidia (40%), Fusarium (35%), Paecilomyces (35%) and Alternaria, Cladosporium, Gliocadium and Mucor (30%). The toxigenic species most frequently found were Penicillium citrinum, Aspergillus flavus and Fusarium nygamai. Only two samples were contaminated by AFB1 with levels of 1 and 14 µg kg. Fumonisin was detected in 40% of freshly harvest samples with levels ranged from 533 µg kg to 933 µg kg. The use of silo bags seems to be an effective tool to store sorghum. However, the presence of toxigenic fungi show that regular screening for mycotoxins levels in silages must be performed to avoid the exposure of animals to contaminated feed and the introduction of these compounds into the food chain.

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