Xylitol production by yeasts isolated from rotting wood in the Galápagos Islands, Ecuador, and description of Cyberlindnera galapagoensis f.a., sp. nov.

Abstract

This study evaluated D-xylose-assimilating yeasts that are associated with rotting wood from the Galápagos Archipelago, Ecuador, for xilitol 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 xilitol production, yield and productivity (27.1 g L-1 xylitol, Yp/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, Yp/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- 025T (=UFMG-CM-Y517T; CBS 13997T). The Myco- Bank number is MB 812171.