Effects of concentration of volatile metabolites from bacteria and germinating seeds on fungi in the presence of selective absorbents.

Abstract

Fusarium oxysporum f. conglutinans, Gelasinospora cerealis, Penicillium viridicatum, Trichoderma viride, and Zygorhynchus vuilleminii were grown on slide cultures supported above cultures of seven bacteria and one actinomycete. Except with Escherichia coli and Nocardia corallina, heavy bacterial growth always inhibited growth and sporulation of the fungi, whereas lighter growth either inhibited, did not alter, or stimulated growth and (or) sporulation, depending on the fungus–bacterium combination. Differential absorption of the volatiles by KOH, KMnO4, charcoal, or soil indicated that different volatiles were produced, that some were inhibitory and others stimulatory, and that at least some of the volatiles were organic. Volatiles emitted by germinating seeds reduced spore formation only in G. cerealis, Penicillium vermiculatum, and Z. vuilleminii, but otherwise had no effect on growth, sporulation, or morphology of the above fungi nor on Aspergillus flavipes or Cunninghamella elegans.