Study of the production of fructose and ethanol from sucrose and molasses media using Saccharomyces cerevisiae ATCC 36858.

摘要

Fructose is available as a component of invert sugar and of high fructose corn syrups (HFCS) in which fructose and glucose are present in nearly equimolar concentrations. This study reports on a new mutant, Saccharomyces cerevisiae ATCC 36858, which is able to produce enriched and pure fructose syrups from synthetic glucose/fructose mixtures, sucrose and raffinose, and from molasses media. In this study, the results showed that S. cerevisiae ATCC 36858 can hydrolyze sucrose, raffinose and melibiose then selectively ferment glucose and galactose to ethanol.; In batch tests, the fructose yield was above 93% of the theoretical value in synthetic glucose/fructose media with a total sugar concentration of 300 g/L. The ethanol yield was about 76% of the theoretical value. The fructose yield was above 90% of the theoretical value in synthetic media with a sucrose concentration up to 726 g/L and in molasses media with a sugar concentration up to 323 g/L. The ethanol yield was between 72 and 85% in synthetic media with a sucrose concentration up to 451 g/L. A lower ethanol yield was obtained in molasses media. The strain of yeast used can be considered osmophilic because it can grow in synthetic media even with a sucrose concentration above 530 g/L. In synthetic media with initial raffinose concentrations between 30 and 242 g/L, fructose and ethanol yields were between 82 and 96%, and 67 and 76%, respectively.; Syrups with more than 97% fructose based on the final total sugar concentrations can be produced from synthetic media with initial sucrose concentrations below 360 g/L. Even at a sucrose concentration of 574 g/L, the produced syrup contained 59% fructose and thus, it was richer in this carbohydrate than the ordinary 55% HFCS. The fructose fractions in the carbohydrate content of the produced syrups was more than 95% when the total initial sugar concentrations in sugar cane and beet molasses media were below 274 and 242 g/L, respectively. Syrups with more than 96% fructose based on the final total sugar concentrations can be produced in media with initial raffinose concentrations below 189 g/L.; The effects of initial biomass, yeast extract and ethanol concentrations, pH, and media sterilization on the production of fructose and ethanol in synthetic sucrose media were also examined. (Abstract shortened by UMI.)