Differentiation of species from the Penicillium roqueforti group by volatile metabolite profiling.

Species from the Penicillium roqueforti group were differentiated by volatile metabolite profiling primarily of sesquiterpenes. A total of 24 isolates from species P. roqueforti, Penicillium carneum, and the recently described species Penicillium paneum were inoculated on yeast extract sucrose agar. Volatile metabolites were collected by diffusive sampling onto tubes containing Tenax TA, overnight between the fifth and sixth days of incubation. Volatiles were thermally desorbed and analyzed by gas chromatography coupled to mass spectrometry. The sesquiterpene area of the chromatogram was investigated, and potential sesquiterpenes were tabulated by comparison of their Kovats retention index and mass spectrum. In general, P. carneum isolates produced the lowest number of sesquiterpenes, all of which were unique for P. carneum within the P. roqueforti group. P. roqueforti and P. paneum produced a larger variety of volatile metabolites, some of which they have in common and some of which are unique for the two species. (+)-Aristolochene was found in samples from P. paneum and P. roqueforti. Other Penicillium species in which (+)-aristolochene was also detected were P. commune, P. glandicola, and P. solitum.