**3.3. Yeasts and molds**

Yeasts and molds are widely diffused eukaryotic microorganisms because of their adaptation to different environmental conditions. Yeasts and molds can cause various degrees of food decomposition. Invasion and growth may occur on virtually any type of food (Beuchat & Cousin, 2001). Their contamination of food can lead to product losses but, in particular, the highest risk is due to the mycotoxin production by the molds. Several yeasts genera may be important for the sensorial properties of fermented products and for their interrelation with *Lactobacillus* bacteria (see section 2.1) in fermented olives. However, film-forming yeasts as *Debaryomyces, Candida, Pichia* and *Endomycopsis*, are often associated with pickled products and vegetable brines (Fleming et al., 2001), representing the cause of olive defects and consequent product losses.

Available media for yeasts and molds count are several: Rose Bengal Chloramphenicol agar, YM agar, Oxytetracycline Glucose Yeast Extract agar, Sabouraud agar and others. When not included in the medium, the addition of 100 mg/L chloramphenicol is recommended to inhibit the growth of bacteria. For simple enumeration of yeasts and molds, the plates should be incubated aerobically at 25°C for 48 hours.
