Effect of carbendazim and water activity on the growth of Aspergillus ochraceus and ochratoxin A accumulation in solid medium containing bee pollen

Bee pollen is a natural, highly appreciated food product due to its high content of proteins and free amino acids. The natural mycobiota occurring in bee pollen and production of mycotoxins in this substrate was previously studied. The efficacy of the fungicide methyl-2-benzimidazol carbamate (carbendazim) to control mycelial extension of an ochratoxigenic strain of Aspergillus ochraceus and its effect on ochratoxin A (OTA) production in bee pollen medium was studied. The effect of different fungicide doses (0.01 − 10 mg/l) at water activities (aw) ranging from 0.99 to 0.94 was studied. A solid medium containing 2% bee pollen, water and agar was used in this study. The highest lag-times (7 days) were observed at 5 mg/l and 0.98 aw. The growth rate of A. ochraceus decreased at fungicide concentration > 2 mg/l. OTA production in cultures was studied as a function of aw and fungicide concentration. The highest OTA level in the medium was found at a dose of 0.2 mg carbendazim /l and at 0.99 aw. Addition of carbendazim at the levels assayed inhibited OTA production in cultures at 0.96 and 0.94 aw.