Identification of citrinin as the defence metabolite of Penicillium corylophilum stressed with the antagonist fungus Beauveria bassiana.

Penicillium corylophilum isolated from mosquitoes was cultivated in liquid media leading to the first reported identification of citrinin (1a) as one metabolic component of this fungus. The produced amount of 1a indicated this compound as the most abundant secondary metabolite of this fungus. Stressing the culture of P. corylophilum with the presence of the antagonistic fungus Beauveria bassiana increased in 65% the production of 1a. Similar results were obtained with the presence of other fungi in the culture media, indicating that citrinin is the main defence metabolite of P. corylophilum. In agreement with this conclusion, citrinin showed a reasonable fungicidal activity against Colletotrichum gloeosporioides and B. bassiana.