Styrene is a well-known fungal volatile metabolite which is produced from phenylalanine. It is also reported as an infection marker of Penicillium expansum, which is a filamentous fungus that is widely present in the natural environment, in some spoiled fruits such as apples and plums. Fruits, especially, apples are major hosts of Penicillium expansum which causes blue mold rot. The objective of this study was to investigate volatile compounds produced by Penicillium expansum and compare the contents of volatile compounds derived from phenylalanine, such as styrene and 2-phenylethanol, at different phenylalanine concentrations and cultivation times. Volatile compounds were extracted using stir bar sorptive extraction (SBSE) method and analyzed by gas chromatography-mass spectrometry (GC-MS) after cultivation in PDB media containing 6 and 12 mM phenylalanine for 24, 48 and 72 hours. At relatively low phenylalanine concentration (6 mM), larger amount of styrene was detected, whereas the level of 2-phenylethanol was considerably higher than that of styrene at relatively high phenylalanine concentration (12 mM). When Penicillium expansum was cultivated for 72 hours, the fungus produced the largest amount of styrene. Also, the contents of other volatile compounds derived from phenylalanine, such as benzaldehyde and acetophenone, were larger compared to other cultivation times. These results showed that the formation of styrene by Penicillium expansum can be affected by phenylalanine concentration and cultivation time.

Effects of phenylalanine concentration and cultivation time on the formation of styrene and volatile compounds by Penicillium expansum

256th National Meeting (2018)

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