Changes in volatile production during the course of fungal mycelial interactions between Hypholoma fasciculare and Resinicium bicolor

The mycelia of two wood decay basidiomycete fungi were grown opposing each other across a 1-mu m pore membrane supported on the surface of malt broth, contained within a sealable reaction vessel. Production of volatiles during the time course of interaction was followed by collecting head space samples by solid phase microextraction (100 mu m polydimethylsiloxane fiber) on five occasions over 25 d following coinoculation of the fungi: 1, 3 (i.e., immediately prior to mycelial contact), 9 (1-2 d after initiation of pigment production by Resinicium bicolor), 17, and 25 d. Ten volatiles were produced during interactions that were not detected in single species controls. In general, most (18) fungal volatiles were sesquiterpenes eluted between 12.5 and 21 min, with a further two eluted at 29.1 and 33.9 min; a benzoic acid methyl ester, a benzyl alcohol, and a quinolinium type compound with a distinctive fragmentation pattern at m/z 203, 204, 206, and 207 were also identified; three volatiles with m/z maxima of 163, 159, and 206-208, respectively, remained unidentified. The results are discussed in relation to possible ecological roles of volatiles.