The effect of culture preservation techniques on patulin and citrinin production by Penicillium expansum Link.

AIMS To study the influence of culture preservation methods and culture conditions on the production of the mycotoxins patulin and citrinin by Penicillium expansum. METHODS AND RESULTS Ten strains of Penicillium expansum were preserved using subculture and maintenance at 4 degrees C, mineral oil, drying on silica gel and freeze-drying. Patulin and citrinin production was assessed on yeast extract sucrose agar (YES) and grape juice agar (GJ), using TLC before and after 0.5, 2-3, 6 and 12 months preservation. Citrinin was detected in all cultures for all preservation techniques on YES. The patulin profiles obtained differed with strain and culture media used. CONCLUSIONS Citrinin production seems to be a stable character for the tested strains. There is a tendency for patulin detection with time apparently more consistent for silica gel storage and freeze-drying, especially when the strains are grown on GJ. SIGNIFICANCE AND IMPACT OF THE STUDY Variability in the profiles of the mycotoxins tested seems to be more strain-specific than dependent on the preservation technique used.