The ability of cylopiazonic acid production expressed by surface moulds isolated from dry cured meat products

Cyclopiazonic acid (CPA) is an under-investigated mycotoxin of toxicological significance, produced by several Penicillium (P. griseofulvum, P. camemberti, P. dipodomyicola and P. commune) and Aspergillus (A. flavus, A. oryzae and A. tamarii) species. Moulds of the Penicillium and the Aspergillus genus overgrow the surface of dry– cured meat products during ripening. Although P. commune is one of the predominant mould species isolated from dry–cured meat products, CPA concentrations in products of this type are generally unexplored. The ability of moulds to produce mycotoxins is affected by various environmental and biological factors, such as the presence and expression of biosynthetic genes. In this study, 200 samples of Croatian traditional dry-cured meat products were analysed for the presence of CPA- producing moulds. Surface moulds were identified using both the traditional and the molecular method, the latter employing beta- tubulin and calmodulin loci sequencing. The isolates of mould species that can produce CPA were tested for the presence of dmaT gene encoding dimethylallyl tryptophan synthase involved in CPA production using the real-time PCR. CPA concentrations in dry-cured meat products were analysed using LC-MS/MS (liquid chromatography- tandem mass spectrometry). Species identified from the surface of TMP samples, potentially able to produce CPA, were P. commune (70 isolates), A. flavus (12 isolates), and P. polonicum (13 isolates). Namely, several studies have indicated the need for testing the CPA production potential of P. polonicum as well. The results revealed the presence of dmaT gene in 17% of A. flavus, 64% of P. commune, and none of P. polonicum isolates. In 24 samples, the CPA concentrations were above the limit of detection (LOD = 2.17 µg/kg) and rose up to 66.35 µg/kg. P. commune comprising dmaT gene was identified in roughly half of the CPA positives (11 out of 24), while A. flavus was not identified in any of CPA-contaminated samples. It can be concluded that P. commune commonly possesses the CPA biosynthetic gene and therefore represents a potential public health hazard. CPA contamination of samples in which P. commune or other CPA producers were not identified can either be explained by the previous contamination of meat product ingredients, or by the possibility that P. commune (or other CPA producers) were overgrown by other mould species at the end of the ripening stage and therefore skipped detection.