Molecular and chemical evaluation of patulin production of Aspergillus and Penicillium-like species isolated from Hungarian apples.

Mycotoxins are secondary fungal metabolites harmful to humans and animals. Patulin (PAT) is a toxin found in different food products but especially in apples and their derivative products. The most common fungi producers of this compound are Aspergillus clavatus and Penicillium expansum. The production of patulin, as other mycotoxins, can be impacted by diverse phenomena such as water and nutrient availability, UV exposure, and the presence of antagonistic organisms. Consequently, gaining a comprehensive understanding of climate and environmental conditions is a crucial step in combating patulin contamination. In this study, moulds were isolated from 40 apple samples collected from seven locations across Hungary: Csenger, Damak, Pallag, Lövőpetri, Nagykálló, and Újfehértó. A total of 183 moulds were morphologically identified, with 67 isolates belonging to the Alternaria, 45 to the Aspergillus, and 13 to the Penicillium groups. The location possessed a higher influence than farming method on the distribution of mould genera. Despite the requirement of higher temperature, Aspergillus species dominated only for the region of Újfehértó with approximately 50% of the isolates belonging to the genus. Four of the seven locations assessed: Csenger, Debrecen-Pallag, Nyírtass and Nagykálló, were dominated by Alternaria species. All isolates belonging to the genera Aspergillus and Penicillium were tested for the presence of the isoepoxidone dehydrogenase (idh) gene, a key player in the patulin metabolic pathway. To guarantee patulin production, this ability was confirmed with TLC assays. The only Aspergillus strain that presented a positive result was the strain Aspergillus clavatus B9/6, originated from the apple cultivar Golden Reinders grown in Debrecen-Pallag by integrated farming. Of the Penicillium isolates only one strain, B10/6, presented a band of the right size (500-600 bp) for the idh gene. Further sequencing of the ITS gene showed that this strain should be classified as Talaromyces pinophilus. The TLC tests confirmed this microorganism as the only patulin producer under the studied conditions for its cluster.