Diagnostic characterization of Penicillium palitans, P. commune and P. solitum

A total of 98 isolates of Penicillium commune and P. solitum were analysed and it was shown that these isolates produced three unique combinations of secondary metabolites. Penicillium commune produced cyclopiazonic acid, cyclopaldic acid and rugulovasine A and B; P. solitum produced compactin and a new group including the ex-type culture of P. palitans produced cyclopiazonic acid and fumigaclavine A. Isolates in all three groups were able to produce cyclopenin, cyclopenol and viridicatin. An optimal thin layer chromatography system to detect the secondary metabolites from P. commune, P. palitans and P. solitum was developed using an agar plug method. The results were confirmed by high performance liquid chromatography with diode array detection. The chemotaxonomic allocations were backed up by differences in conidial colour on Czapek yeast autolysate agar, reverse colour on yeast extract sucrose agar and origin of the isolates. Even though P. palitans previously has been considered synonymous with P. commune or P. solitum it was concluded that P. palitans is a distinct species.