Characterization of Volatile Organic Compounds Released by Penicillium expansum and Penicillium polonicum

Background/Objectives: Fungi produce a diverse array of metabolites, including various volatile organic compounds (VOCs) with known physiological functions and other biological activities. These metabolites hold significant potential for medical and industrial applications. Within the fungal domain, Penicillium species represent a particularly important group. Methods: This study characterized the VOC profiles of four Penicillium expansum strains (R11, R19, R21, and R27) and one Penicillium polonicum strain (RS1) using the solid-phase microextraction–gas chromatography–mass spectrometry technique. Results: The analysis revealed that the only compound in common among the five strains of Penicillium was phenyl ethanol. The high toxicity of P. polonicum RS1 to Drosophila larvae correlated with its diverse and abundant alkene production. Specifically, alkenes constituted 31.28% of its total VOCs, followed by alcohols at 29.13%. GC-MS analyses detected 22, 17, 22, and 18 specific VOCs from R11, R19, R21, and R27, respectively. Overall, alkenes dominated the R11 profile (17.03%), alcohols were most abundant in R19 (28.82%), and R21 showed the highest combined release of alcohols (23.2%) and alkenes (11.7%), while R27 produced a moderate abundance of alcohols (9.16%) and alkenes (4.19%). Among the P. expansum strains, R11, R21, and R27 exhibited substantially higher toxicity than R19 strain in our previous assessment; these findings are consistent with their respective VOC profiles. Conclusions: The distinct VOC compositions across Penicillium strains significantly influence their biological characteristics and ecological functions. These findings provide a basis for follow-up research into the mechanisms of fungal volatile-mediated toxicity and support the development of biocontrol strategies.