Identification of Yeasts Isolated from Bread Dough of Bakeries in Shiraz, Iran

Eighty-one yeast cultures isolated from 43 different bakeries in Shiraz, Iran, were studied for their morphological, sexual and physiological characteristics. Seventy-four of the cultures formed ascospores on 13 different media. They exhibited morphological and physiological characteristics similar to nine different species in the genus Saccharomyces . Thirty-four of these 74 yeast cultures were similar to Saccharomyces cereviseae , 18 to Saccharomyces chevalieri , nine to Saccharomyces rosei , four to Saccharomyces ellipsoideus , three to Saccharomyces telluris , two to Saccharomyces pretoriensis , two to Saccharomyces kluyveri , one to Saccharomyces exiguus and one to Saccharomyces inconspicuus . Based on their morphological and physiological characteristics, four of the seven non-sporulating yeast cultures were similar to Saccharomyces chevalieri , two to Saccharomyces cervisease and one to Saccharomyces rosei . A comparative study was also made between the usual tube method of cycloheximide sensitivity testing of yeasts and the standard single disk technique with solid media as used for antibiotic susceptibility testing of bacteria. The disk method was applicable to yeasts and had advantages over the tube method.