Ochratoxin A producingPenicillium verrucosumisolates from cereals reveal large AFLP fingerprinting variability.

j.c. frisvad, f. lund and s. elmholt. 2004.To examine if molecular amplified fragment length polymorphism (AFLP) fingerprinting of the only ochratoxin A-producing species in European cereals,Penicillium verrucosum, can be used as a method in hazard analysis using critical control points (HACCP).A total of 321 isolates ofP. verrucosumwere isolated from ochratoxin A-contaminated cereals from Denmark (oats), UK (wheat and barley) and Sweden (wheat). Of these, 236 produced ochratoxin A as determined by thin layer chromatography; 185 ochratoxin A-producing isolates were selected for AFLP fingerprinting. A total of 138 isolates had unique AFLP patterns, whereas 52 isolates could be allocated to small groups containing from two to four isolates with similar AFLP patterns. A total of 155 clones were found among the 185P. verrucosumisolates, thus 84% of the isolates may represent different genets ofP. verrucosum. As the few isolates that were grouped often came from the same farm, and those groups that contained AFLP-identical isolates from different countries were morphotypically different. On single farms up to 35 clones were found. The few groups of ramets from the same genet indicated that a HACCP approach based on clones may require a very large number of AFLP analysis to work in practice, we recommend basing the HACCP approach on the actual speciesP. verrucosum. A more detailed characterization should rather be based on the profile of species present at different control points, or analysis of the mycotoxins ochratoxin A and citrinin in the isolates. Examination of 86 isolates with HPLC and diode array detection ofP. verrucosumshowed that 66% produced ochratoxin A, 87% produced citrinin, 92% produced verrucin and 100% produced verrucolone.Among 184 ochratoxin A-producingPenicillium verrucosum, 155 clonal lineages were indicated by AFLP fingerprinting, indicating a high genetical diversity, yet the speciesP. verrucosumis phenotypically distinct and valid.AFLP fingerprinting ofPenicillium verrucosumindicates that genetic recombination takes place in this fungus. [ABSTRACT FROM AUTHOR]