pr-toxin and aristolochene

Volatile metabolites that might accompany production of PR toxin by Penicillium roqueforti were investigated. Volatiles and PR toxin were evaluated for 16 strains of P. roqueforti. Solid phase microextraction was used for isolation of volatiles. Thirteen strains produced PR toxin, and all of them produced a specific set of sesquiterpene hydrocarbons including (+)-aristolochene-an intermediate in PR toxin biosynthesis, beta-bisabolene, alpha-chamigrene, diepi-alpha-cedrene, beta-elemene isomer, beta-elemene, beta-gurjunene, beta-himachalene, alpha-panasinsene, beta-patchoulene, beta-patchoulene isomer, alpha-selinene, and valencene. Aristolochene and the remainder of the sesquiterpene hydrocarbon profile were unique for P. roqueforti producing PR toxin. They were absent in nontoxigenic P. roqueforti and in 40 strains of other Penicillium species. Volatile compounds, sesquiterpene hydrocarbons, and aristolochene paralleled PR toxin synthesis. Incubation temperature (20, 24, or 27 degrees C) and water content in the medium (20, 30, or 40%) influenced the amount of produced sesquiterpenes, but not their profile, suggesting it is species specific. The sesquiterpene hydrocarbon pattern and especially aristolochene can be used as volatile markers for detecting the process of undergoing biosynthesis of PR toxin by P. roqueforti.

Topics: Culture Media; Naphthols; Penicillium; Sesquiterpenes; Species Specificity; Temperature; Volatilization

The effect of wheat kernel medium supplementation with octanoic acid on the formation of PR toxin and some volatiles by Penicillium roqueforti was investigated.. Octanoic acid was added to the medium once, prior to inoculation (4.55 mg g-1), or periodically (total 27.3 mg g-1) during the 10 day course of incubation. No octanoic acid was added to the reference sample. Levels of 2-heptanone, 2-heptanol and aristolochene, a volatile intermediate in PR toxin biosynthesis, were monitored using a solid phase microextraction (SPME) technique. The contents of PR toxin and ergosterol were determined after incubation. Aristolochene was observed in the reference sample, and 10.4 mg kg-1 of PR toxin was detected after 10 days. In cultures periodically supplemented with octanoic acid, no aristolochene or PR toxin were observed. However, in samples supplemented with octanoic acid only prior to incubation, the aristolochene level was 25% that in the reference sample, and PR toxin content was 3.4 mg kg-1.. These data suggest that a high level of octanoic acid in the medium prevents PR toxin formation by P. roqueforti.

Topics: Caprylates; Culture Media; Ergosterol; Ketones; Naphthols; Penicillium; Sesquiterpenes; Triticum