4.5. Analysis of Antifungal Activity of Volatile Organic Compounds (VOCs)

The production of VOCs with putative AF activity was tested by using the double-dish chamber test [64]. Briefly, two sterile bottom dishes of Petri dish (9 cm in diameter) were used. One dish contained Potato Dextrose Agar (PDA) medium (Sigma-Aldrich) that was inoculated with a 9 mm diameter agar plug containing V. dahliae. Another dish contained a Streptomyces sp. culture grown in MEY agar medium [55] at 30 °C until a good sporulation was obtained (normally 3–5 days) depending on the strain tested. The two plates were faced so that the plate inoculated with the fungus was placed inverted on the plate inoculated with the bacteria. Both dishes were sealed with Parafilm and incubated at 25 °C for 14 days. Then, the inhibition index was calculated as indicated above.