Isolation and Identification of Fusarium Species from Maize and Wheat and Assessment of Their Ability to Produce Fumonisin B1

Fusarium species are prevalent contaminants of foodstuffs and agricultural crops. They produce fumonisins، which are carcinogenic mycotoxins. The present study has evaluated maize and wheat samples from ten provinces in Iran that were contaminated with Fusarium species. Special attention was paid to the ability of the isolates to produce fumonisin B1 (FB1) as a public health hazard. We collected 32 maize and 15 wheat samples from ten provinces that were major cultivation areas. Samples surface disinfected with a 1% sodium hypochlorite solution for 2 minutes. Fusarium species were isolated by the flotation method on malachite green agar. Pure cultures on potato dextrose agar (PDA) were identified using a combination of macroscopic and microscopic morphological criteria. The ability of the isolates to produce FB1 was evaluated by thin layer chromatography (TLC) and the amounts of fumonisin B1 produced were assessed by high performance liquid chromatography (HPLC). A total of 55 Fusarium isolates that belonged to five species were isolated. There were 27 of the 32 maize samples (84. 4%) and 11 of 15 wheat samples (73. 3%) that were contaminated with Fusarium species. Species consisted of F. verticillioides (23 isolates)، F. proliferatum (22 isolates)، F. subglutinans (5 isolates)، F. nygamai (4 isolates) and F. redolens (1 isolate) based on morphological criteria. Twenty-two of the 55 (40%) Fusarium isolates produced FB1 in a total range from 230. 4 to 9565 µg/ml. The highest amounts of FB1 production were related to toxigenic isolates of F. verticillioides and F. proliferatum. Results of the present work indicates a high degree of contamination of maize and wheat with Fusarium strains that belong to the Gibberella fujikuroi species complex وparticularly F. verticillioides and F. proliferatum. This contamination is a potential public health threat due to food spoilage and subsequent production of high levels of carcinogenic FB1.