Distinct volatile profiles of Metschnikowia pulcherrima L672 and Hanseniaspora uvarum L793 determine their antagonistic efficacy against Aspergillus flavus in a dried fig agar model.

Contamination of dried figs by Aspergillus flavus and its carcinogenic aflatoxins poses a significant food safety risk. Volatile organic compounds (VOCs) from biocontrol yeasts offer a promising sustainable alternative to synthetic fungicides. This study aimed to evaluate the effect of VOCs produced by Metschnikowia pulcherrima L672 and Hanseniaspora uvarum L793 on the growth and aflatoxin production of A. flavus in a dried fig agar model. The volatile profiles produced by the yeasts, both individually and during co-culture, were characterized by HS-SPME-GC-MS to correlate them with the observed antagonistic activity. The results showed that VOCs from both yeasts potently inhibited mycelial growth by over 94%. However, significant differences were observed in their anti-aflatoxigenic efficacy. While M. pulcherrima L672 significantly reduced aflatoxin levels, H. uvarum L793 reduced their synthesis to below the limit of detection. This distinction was strongly correlated with their volatile profiles; H. uvarum L793 produced a more complex and abundant blend of VOCs, particularly alcohols and esters, in response to the fungus. In conclusion, our findings demonstrate that while both yeasts are effective fungistatic agents, the superior anti-mycotoxigenic activity of H. uvarum L793 is correlated with a more robust and complex volatile response to the pathogen. This highlights the critical role of the specific volatilome composition in determining biocontrol efficacy and positions H. uvarum L793 as a prime candidate for controlling A. flavus in food systems.