Yeasts Occurring on Dates

Abstract

67 cultures of yeasts were isolated from California and Egyptian dates undergoing microbiological deterioration. Most of the organisms isolated were cultures of Zygosaccharomyces, Hanseniaspora and Candida. The species of Zygosaccharomyces in order of occurrence were Z. japonicus var. soya (20), Z. barken (8), Z. globijormis (1), and Z. nadsonii (1). All spp. of Hanseniaspora (18) were identified as H. melligeri. Other perfect genera obtained are Saccharomyces, Pichia and Hansenula. Saccharomyces was represented by 2 cultures, S. cerevisiae and S. carlsbergensis var. polymorphus. The 3 cultures of Pichia were described as P. chodati var. fermentans. The single culture of Hansenula was H. subpelliculosa. Of the imperfect yeasts the genus Candida was most common, 5 being C. chalmersi, 2 C. tropicalis, 1 of C. krusei and an unidentified species. Torulopsis dactylifera is described. All cultures of Zygosaccharomyces were more sugar-tolerant than the other yeasts isolated.