This study evaluated D-xylose-assimilating yeasts that are associated with rotting wood from the Galápagos Archipelago, Ecuador, for xylitol production from hemicellulose hydrolysates. A total of 140 yeast strains were isolated. Yeasts related to the clades Yamadazyma, Kazachstania, Kurtzmaniella, Lodderomyces, Metschnikowia and Saturnispora were predominant. In culture assays using sugarcane bagasse hemicellulose hydrolysate, Candida tropicalis CLQCA-24SC-125 showed the highest xylitol production, yield and productivity (27.1 g L(-1) xylitol, Y p/s (xyl) = 0.67 g g(-1), Qp = 0.38 g L(-1). A new species of Cyberlindnera, strain CLQCA-24SC-025, was responsible for the second highest xylitol production (24 g L(-1), Y p/s (xyl) = 0.64 g g(-1), Qp = 0.33 g L(-1) h(-1)) on sugarcane hydrolysate. The new xylitol-producing species Cyberlindnera galapagoensis f.a., sp. nov., is proposed to accommodate the strain CLQCA-24SC-025(T) (=UFMG-CM-Y517(T); CBS 13997(T)). The MycoBank number is MB 812171.

Chicha, a type of beer made mainly with maize or cassava, is a traditional fermented beverage of the Andean region. There have only been a few studies on yeasts associated with chicha fermentation, and the species diversity occurring during the production of this beverage is not known. The objective of this study was to determine the biodiversity of yeasts in chicha, and to characterize the Saccharomyces cerevisiae populations associated with the production of chicha de jora, seven-grain chicha, chicha de yuca, and chicha de morocho in Ecuador. The molecular diversity of S. cerevisiae populations was determined by restriction polymorphism mitochondrial profiles. The beverages were characterized based on their physicochemical parameters. Twenty-six species were identified, and the most prevalent species were S. cerevisiae and Torulaspora delbrueckii. Other yeast species were isolated at low frequencies. Among 121 isolates of S. cerevisiae, 68 different mtDNA molecular profiles were identified. These results showed that chichas are fermented by a high number of different strains of S. cerevisiae. Some other species provided a minor contribution to the fermentation process. The chicha presented generally similar physicochemical parameters to those observed for other traditional fermented beverages, and can be considered as an acid fermented beverage.