An Overview of Fungal Volatile Organic Compounds (VOCs)

Fungi emit many volatile organic compounds (VOCs) as mixtures of low molecular mass alcohols, aldehydes, esters, terpenoids, thiols, and other small molecules. The study of the gas-phase portion of a metabolome is sometimes called “volatomics.” Chemical separation and VOC identification usually rely on gas chromatography-mass spectrometry (GC-MS). Fungal VOC profiles are both complex and dynamic: the specific compounds produced and their abundance vary with the producing species, the age of the colony, water availability, the substrate, the temperature, the presence of other organisms, and other parameters. The single most reported volatile from fungi is 1-octen-3-ol. It functions as a hormone within many fungal species; serves as both an attractant and a deterrent for some species of arthropods; and exhibits toxicity at relatively low concentrations in several model systems. Fungal VOCs have been studied by scientists from a broad range of subdisciplines in both theoretical and applied contexts. In biotechnology, VOCs are exploited for their food and flavor properties as indirect indicators of microbial growth, to stimulate plant growth, and to attract insect pests. Because these compounds can diffuse a long way from their point of origin, they are excellent chemical signaling molecules and facilitate the ability of fungi to engage in “chemical conversations.” Volatiles shape ecology at the level of organisms and populations. The physiological effects of fungal VOCs in host–pathogen relationships and mediating interspecific associations in natural ecosystem functioning are emerging frontiers in volatile research.