Effect of Methods of Preparation upon Fermentative Activity of Yeast Zymin

Abstract

Stavely, Christensen and Fulmer, , , presented data on the effect of several electrolytes and of ethanol upon the fermentative activity and phosphate content of yeast zymin. The zymin was prepared from brewers'yeast (furnished by Anheuser-Busch of St. Louis) by the procedure outlined by Harden. Five hundred grams of yeast and 3 liters of acetone were stirred together for 10 minutes and filtered on a Buchner funnel. The mass was then mixed with one liter of acetone for 2 minutes and again filtered. The residue was coarsely powdered, stirred with 250 cc. of ether for 3 minutes, filtered, and spread out on paper in a thin layer. After standing for one hour at room temperature it was dried for 24 hours at 40-45°. The present communication deals with data on several factors as they affect the activity of the zymin preparation. The apparatus of Harden, Thompson and Young, with some modification, was employed in the determination of the evolution of carbon dioxide. The inorganic phosphate was determined colorimetrically by the revised procedure of Kuttner and Lichtenstein. Detailed procedure and technique are given in reference 2. It was noted by Stavely, Christensen and Fulmer that the fermentative activity of the zymin increased with the time of storage, in the refrigerator, of the yeast from which it was made. The increase was paralleled by increase in free inorganic phosphate and in the rate of esterification of the phosphate in the presence of dextrose. In Tables I and II are given more detailed data with reference to the points noted above. The yeast was stored at 5°.