2.4. In vitro evaluation of volatile organic compounds (VOCs)
To ascertain whether VOCs produced by the antagonistic yeast strains may have a role in A. carbonarius inhibition, yeast and pathogen cell suspensions were prepared as described previously, by using two distinct A. carbonarius strains MPVA566 and AN6 (isolated from grape, courtesy of Professor G. Romanazzi and Dr. E. Feliziani, Università Politecnica delle Marche, Ancona, Italy).
YPD agar (2%) plates were inoculated by evenly streaking 100 μL of yeast cell suspension (108 CFU/mL) using a sterile spreader and incubated for 24 h at 25 °C. The plate lid was then replaced by a Petri dish containing PDA point-inoculated with 20 μL of pathogen spore suspension (107 conidia/mL), sealed with Parafilm® and examined after 5 days of incubation at 25 °C by evaluating the radial growth and the morphology of A. carbonarius colonies. Three replicates for each fungus–yeast combination were set and each experiment was repeated twice.