In Vitro Analysis of Volatile Headspaces Involving Aspergillus spp. of Agricultural Importance

Authors: Moore, Geromy; Lloyd, Steven

Submitted to: Chemistry and Biodiversity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2025
Publication Date: 8/30/2025
Citation: Moore, G.G., Lloyd, S.W. 2025. In vitro analysis of volatile headspaces involving Aspergillus spp. from different geographical regions reveals extensive variation. Chemistry and Biodiversity. https://doi.org/10.1002/cbdv.202501467.
DOI: https://doi.org/10.1002/cbdv.202501467

Interpretive Summary: Fungi produce metabolites to aid in their survival. These compounds have a history of being exploited for the benefit of humanity. It is unknown if strains of a fungal species (in this case Aspergillus flavus) produce the same (or different) metabolites when colonizing a food source, or if unique metabolites are produced that could be exploited for benefit. Previously, our lab captured and characterized volatilized fungal metabolites, emitted as gases (VOCs), of four different Aspergillus strains from Louisiana. In this study, we repeated VOC capture experiments using an expanded pool of Aspergillus strains originating from states other than Louisiana. We observed extensive variation in the VOCs produced, including among strains from the same state while growing on the same food source, and variability by the same strain while growing on different food sources. An abundant and diverse collection of VOCs were captured, some of which were unique to A. flavus strains that naturally do not produce aflatoxin (i.e., biocontrol strains). These VOCs could be tested for inhibitory properties and support the efficacy of A. flavus biocontrol. Some VOCs were unique to A. flavus strains (and other species) that produce aflatoxin, which could serve as indicators for the presence of these harmful fungi and allow for early treatment.

Technical Abstract: Using four Aspergillus strains (one non-aflatoxigenic and three aflatoxigenic) from each of three geographic regions (Arizona, Georgia and Mississippi), we conducted experiments whereby each strain was incubated in vials containing one of five different substrates: yeast extract sucrose (YES) medium, mixed grain agar, Czapek's medium, corn meal agar, or cracked kernels from two genotypes of corn (A. flavus susceptible VA35 and A. flavus resistant MI82). The strains were incubated at 30C for up to two weeks before being subjected to SPME/GC/MS to capture the VOCs present in the headspace. MassHunter software was used to identify the compounds present. We observed extensive variation in the VOCs produced. YES medium facilitated production of the greatest number of VOCs, followed by mixed grain agar, then Czapek's medium and corn meal agar medium. Both corn genotypes facilitated production of only one VOC that could be considered fungal in origin. A pool of 10 VOCs were only captured in the headspaces of non-aflatoxigenic strains, which could be examined in future studies for biocontrol properties. Thirteen VOCs were captured only in the headspaces of aflatoxigenic strains, which could be examined in future studies as biomarkers for infection in crops.