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United States Department of Agriculture

Agricultural Research Service

Title: Evaluation of Culture Conditions for Production of Patulin by Penicillium Species

Authors
item Dombrink Kurtzman, Mary Ann
item Blackburn, Judith

Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 15, 2004
Publication Date: September 27, 2004
Citation: Dombrink Kurtzman, M.A., Blackburn, J.A. 2005. Evaluation of several culture media for production of patulin by Penicillium species. International Journal of Food Microbiology. 98:241-248.

Interpretive Summary: The fungus Penicillium expansum is often mentioned as being responsible for patulin production in apples and apple products. The present research was performed to determine which fungal strain and growth conditions were able to produce the greatest amount of the mycotoxin patulin in liquid culture. Eleven strains of Penicillium species were selected and evaluated. A total of six different growth media were compared, examining the amount of patulin produced at four different time points. There was some variability among the different strains regarding the amount of patulin produced, as well as which type of growth medium was best for a particular fungus. In most of the cases, potato dextrose broth supplemented with manganese was the best growth medium for producing patulin. The greatest amount of patulin was produced by all three of the P. griseofulvum isolates, rather by P. expansum as predicted. The impact was to identify high yielding strains for further studies of methods for prevention of patulin in foods and beverages. This research impacts apple growers and producers, and enhances food safety, by providing them with information on fungal strains likely to produce the greatest amount of the mycotoxin patulin.

Technical Abstract: The aims of this work were to evaluate different species of Penicillium to identify those which have the potential to produce the greatest amount of the mycotoxin patulin. Additionally, six different culture media were compared to determine maximum patulin production. Ten different strains of Penicillium species were selected for study because they had previously been reported to be patulin producers. The strains included Penicillium expansum, P. griseofulvum (formerly P. urticae), P. clavigerum and P. coprobium and a recent P. expansum isolate from an apple. Cultures were grown in duplicate in three different liquid media, potato dextrose, malt extract and glucose-yeast extract-peptone, both with and without manganese supplementation. Patulin production was compared at 24, 48, 72 and 96 h. Variability in patulin production occurred among the different species, the growth media used and time of incubation. All three of the P. griseofulvum isolates were the highest producers of patulin at 96 h. For most of the strains, potato dextrose broth supplemented with manganese was optimal for maximum production of patulin. Although P. expansum is frequently cited as the most likely source of patulin in apple juice, certain other Penicillium species are capable of producing more patulin than strains of P. expansum. Therefore, the apple juice industry should be alert to the possibility that organisms other than P. expansum can be responsible for the occurrence of patulin.

Last Modified: 10/21/2014
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