Efficacy of agar media for enumerating two Saccharomyces species in sucrose syrups

Experiments were carried out to determine the suitability of acidified and antibiotic-supplemented agars for supporting colony formation by cells ofSaccharomyces cerevisiae andSaccharomyces rouxii. Yeasts had been suspended in sucrose syrups buffered at pH 3.0, 5.0 and 7.0, and stored at 4 and 21°C for periods of time ranging to 10 weeks. TheSaccharomyces species were recovered in equal numbers, regardless of the type of enumeration agar. Sucrose, at concentrations up to 60%, protected cells against inactivation during storage, and survival was greater at 21° than at 4°C.