5, Wis* olyzate by S. cerevisiae XS^ood sugar solutions produced by the hydroly sis of Douglas fir sawmill waste contain inhibiting substances that make them difficult to ferment by the procedures usuallyused in fermentation industries.Previous reports showed that it was helpful to remove furfural produced by the decomposition of pentose sugars. The use of large quantities of yeast was also helpful. This report shows that neutralized wood hydrolyzates ferment more readily if they are p re treated with aluminum chloride, or if they are produced under conditions of rapid sugar removal to prevent decomposition. Pilot plant fermentations of Douglas fir hydrolyzates used Saccharomyces cerevisiae in batches from 7 liters to 300 gallons. Yeast was transferred without PREVIOUS work at this laboratory demonstrated that the sugars produced by the saccharification of wood could be used to propagate yeast and produce ethyl alcohol by fermentation, provided that treatments were given, or conditions used, which overcame the effect of some of the inhibiting materials in the wood sugar hydrolyzates. Leonard and Hajny (5) demonstrated that addition of sodium bisulfite, a heat treatment at neutrality, or the use of large quantities of inoculum aided in overcoming the effect of the inhibiting materials. Peterson and co-workers (6) found that the use of a rich inoculum was beneficial to the growing of yeast on wood hydrolyzates. Grondal and Berger (Ü) found that removal of lignin and furfural, plus the addition of autolyzed yeast, aided in the butanol fermentation of waste sulfite liquor. Sjolander, Langlykke, and Peterson (.9) found that clarification of the solutions with activated carbon produced solutions that were easily fermented. Many other notable contributions have been made by others, especially in connection with the Scholler process for wood saccharification in Germany (8).Many improvements which affect the ease of fermentation have been made in the wood saccharification process developed at this laboratory (7, 3). Hydrolyzates prepared by these processes were used for study in these experiments.The need for the removal of furfural from liquors to be fermented was pointed out by Leonard and Hajny (5) and by Heuser (4). In recent work at this laboratory a method of flashing the hydrolyzate after neutralization has been used. This procedure removes all but traces of furfural and, at the same rime, permits removal of calcium sulfate at elevated temperatures.This report describes the effect of these changes on the ease of fermentation, and reports a study of the problems connected with pilot plant scale fermentations, such as yeast requirements, conditions for growth of yeast, methods for removing yeast from the fermented liquors, nutrient requirements for growing yeast and for fermentation, etc.The yeast used was a strain of Brewer's yeast S. cerevisiae, No. 49, from the University of Wisconsin collection, selected because of its high alcohol-yielding capacity. Wood hydrolyzates were prepared according to procedures des...
A yeastlike fungus, probably belonging to the genus Torula , was isolated from fresh pollen and was shown to produce erythritol in yields of 35 to 40% of the sugar utilized. The ability to produce erythritol is an inherent characteristic of the isolate, but unfavorable fermentation conditions can lead to the production of glycerol at the expense of erythritol. By the use of a synthetic medium, it was shown that the concentrations of both nitrogen and phosphorous in the medium must be closely controlled to obtain satisfactory erythritol yields.
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