Mycotoxigenic potential of Penicillium species isolated from fresh chestnuts and derived products.

Species of genus Penicillium produce a great variety of secondary metabolites, including mycotoxins. This characteristic is associated with the presence of biosynthetic enzymes organized in biosynthetic gene clusters (BGCs). In the present work, the genomes of ten Penicillium species isolated from fresh chestnuts and derived products were sequenced and annotated. Predicted protein sequences were pooled with those of previously annotated Penicillium spp. and outgroup species in the Eurotiales order to generate phylomes. Phylome data was parsed using the protein sequence of enzymes experimentally associated with the production of target mycotoxins (patulin, andrastin A, mycophenolic acid, penitrem A, meleagrin and verrucosidin) to identify putative homologues in the new strains’ proteome. Production of associated mycotoxins was verified by both HPLCDAD and HPLC-MS/MS on whole mycelium extracts. Results of bioinformatic analyses showed the presence of a complete andrastin A cluster in Penicillium bialowiezense, Penicillium crustosum, Penicillium glandicola and Penicillium taurinense; a complete mycophenolic acid cluster in P. bialowiezense; a complete penitrem A cluster in P. crustosum and P. glandicola; a shortened, biosynthetically active roquefortine C cluster in P. crustosum and P. taurinense, as well as a complete meleagrin cluster in P. glandicola. In addition, putative partial andrastin A clusters from Penicillium palitans and Penicillium discolor were subsequently identified as an atlantinone A cluster. For all of them, chemical analyses confirmed production of the associated metabolite. These results elucidate the genetic bases of mycotoxin production and permit the evaluation of the evolution of BGCs in different species of Penicillium spp.