Fusarium verticillioides (Sacc.) Nirenberg is among the most common Fusarium species corn pathogens worldwide, and has been recognized as a fumonisin B 1 (FB 1 ) and fumonisin B 2 (FB 2 ) producer. In the present work, extracts of 58 F. verticillioides isolates from corn samples collected from Sohag Governorate, Egypt, were tested for their biotoxicity and production of fumonisin toxins. Forty-four Fusarium verticillioides isolates out of 58 tested produced FB 1 or FB 1 and FB 2 (15 and 29

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... tes, respectively) on potato-sucrose agar medium, detected by TLC, whereas the other 14 isolates did not produce fumonisin toxins. HPLC crude extract analysis confirmed the results from TLC plates. Brine shrimp larvae as well as the Gram-negative bacteria Pseudomonas aeuroginosa showed low bio-sensitivity towards the F. verticillioides crude extract toxicity, whereas the Gram-positive bacteria Bacillus cereus and Bacillus subtilis, especially B. subtilis, showed higher sensitivity towards the tested Fusarium crude extracts. These results enabled us to bio-evaluate and chemically detect fumonisin mycotoxins using a simple agar medium technique. cultivated on PSA medium under aseptic conditions, using 15 cm Petri dishes (Bailly et al., 2005) , and incubated at 20±2 uC for 5 days. At the end of the incubation period, all plates were transferred into a refrigerator for 10 days. The agar media with mycelium were cut into small pieces (1 cm 2 ), transferred into 250 ml Erlenmeyer flasks Abbreviations: FB 1 , fumonisin B 1 ; FB 2 , fumonisin B 2 .