A qualitative and semi-quantitative study of volatile organic compounds released by mycotoxin-producing strains of Aspergillus flavus.

In recent years, an exponential interest in the study of secondary metabolites of fungi has emerged in order to understand their functioning and to valorise them. Volatile organic compounds (VOCs) are one of them. What VOCs could tell us about the state of development of the fungus but also about its toxicity?

The filamentous fungus Aspergillus flavus, grows in the field or during the storage of cereals. In addition to damaging the crop, some strains of this fungus have the ability to produce mycotoxins named aflatoxin. The most common aflatoxin produced by Aspergillus flavus is aflatoxin B1 (AFB1). AFB1 is a small, non-volatile, heat-stable molecule that has a very high toxicity at low concentrations. This mycotoxin can cause illness and potentially death for consumers.
Faced with real health issues, quality analyses (HPLC and ELISA tests) are carried out, but these require specific equipment and qualified staff. Moreover, this equipment is not very mobile and is expensive.

A qualitative and semi-quantitative comparison of the VOCs emitted by Aspergillus flavus strains producing AFB1 (toxigenic strain) and not producing AFB1 (non-toxigenic strain) was performed over several days. The VOCs were extracted using SPME fibres to obtaina wide range of VOCs belonging to thevarious molecular family of molecules emitted by fungi. After extraction, the compounds were separated by gas chromatography and identified by mass spectrometry. The purpose of this work is to try to indirectly correlate certain VOCs with the production of AFB1 in foodstuffs.

Common VOCssuch as 3-methylbutan-1-ol, 2-methylpropan-1-ol, 3-methylbutanal, already known in the literature were detected. But, we also highlighted the emission of terpenes (epizonaren, δ-cadinene) specifically by toxigenic strains. Today, interesting VOCshave been identified. However, this work is only at the beginning and further work will be necessary to link aflatoxin production and specific VOCs emission.