ペントースの醗酵化學的利用に關する硏究 : ペントース同化性酵母に就て

Abstract

In the previous papers1) our studies on alcoholization of saccharified solution of cellulose materials by Scholler's method were reported. Pentose-assimilable yeasts were isolated in spent wash obtained from the saccharified solution of Mulberry-tree added with d-xylose and in an artificial medium containing d-xylose as the only source of carbon. Among various kinds of materials including corn, waste parts of vegetables, potato, rice hulls, barley straw, rice straw, stablemanure and soil, the most usefull strains of yeast No.100, 103 and 107 were isolated from the former three materials respectively, from which better yield was obtained compared with the known yeast Torula utilis. Any noticeable difference was never pointed out on the chemical constituents of yeast cells, therefore these yeasts would be useful for food-stuff. From the characteristic natures, these yeasts were found to belong to new strains of Torulopsis according to Lodder's classification, and we named the yeasts No. 100, 103 and 107 Torulopsis xylinus a, b and c respectively. The spent wash (pH5.5), the distillery waste liquor of the alcohol solution obtained from the saccharified solution of mulberry-tree, contained 2.043g organic matters, 0.633g reducing sugars(as glucose), 0.470g pentose and 0.084g total nitrogen in its 100c.c. In order to know the availability of these constituents for yeast, experiments were carried out in the spents wash added by Reader's nutrients, with three strains of pentose-assimilable yeast isolated by us and with Torula utilis previously acclimatized to pentose. During 120 hour ordinary culture at 30℃, 1/3 parts of reducing sugars including more than 2/3 parts of pentose were consumed. It was pointed out that small amount of organic matters other than sugars was assimilated, and noticeable toxic substance was never detected. In case of shaking-culture, the amount of sugar remained and the yield of yeast were observed on 12, 18, 24 and 36 hour incubations. The yield of yeast, especially newly isolated yeast No. 107, attained to a maxium on 24 hour cuture, when 41-46%, 30% and 75% yields of yeast were observed as the organic matters, total nitrogen and pentose respectively. The chemical compositions of the yeast (7-9% ash, 43-47% crude protein thus obtained) were found to be very much the same as the yeast obtained from the spent washes of ordinary wood or pulp waste liquor. 1) Katagiri and Tatsumi: This Bulletin 15, 16, 17, 18 19, and 20.