June, 1946
INDUSTRIAL AND ENGINEERING CHEMISTRY
culty. The selection of a toxic v,ith tlicscx eharacteri,Gtics is tllr first step toward the resolution of the dilcnmia of Toung (121. T h e solubility of cuprous oxide will be compared \vith tho-1%( ~ f other antifouling toxic's i n t h e cmd paper of this series (38.
617
Kett,Iiiini. B. H . . l-euy. J . I>.. Itedfield. .1.C . , and BIII.LLS, A I-.. J r . . Isu. lion products are d r o l y z d hy acid xhich intli(*:it P. ail equi1il)riurn h:~tn-c*cnre\
study of .such unfemientable retiirc.iilg i ) t ~ o : ~ ui~i i ~the t :ti-tillery slops from molas,ies is reported by Battler anti Zvi~ban11.3). The yield of new yeast crop may be ubtained fI'iJn1 Tat)ic I by deducting the dry weight, of the inocula from the total thy n-cight of yeast obtained aftcr the 24-hour growth period. Thi.: is for llycotorula, Hansenula, and Torula, 0.33, 0.33, and O.:39c;', respectively. Calculated on the basis of the dry weight of .ugar consumed, the yield correspondingly ranges from 53 t o G3yO',.A part of this yeast growth may probably be attributed t o the partial consumption of the acids present in the liquor ( 5 ) . T h e slightly greater yield of Torula yeast for this run is only indicative of some variations and was not consistently observed. The ability of Torulopsis utilis 3 t o utilize arabinose \yas investigated earlier (6). I n the present study experiments were niaclo t o ascertain the ability of llycotorula and Hanscnula to utilize thi.; pentose. For this purpose the multiplication of yeast cells and the reduction of the sugar content of media, t o ~vliichdarabinose (levorotatory) had been added, was followed. These findings arc given in Table 11. The data show that under the conditions of the experiments IIycotorula and Hansenula have the capacity t o multiply and remove arabinose from solution. This growth and conmmption of arabinose is not. so rapid as with the sugar in the still viaste liquor and is faster when such sugar is present with the arabinose. The observation that Hansenula is able t o utilize arabino-c is contrary to the findings of Kise and Appling (18) T h o usetl this organism t o assay xylose in the presence of arabinose. Experiments in this laboratory indicate t h a t this organism multiplies much more rapidly in a xylose t h a n in a n arabinose medium, eqpocially when freshly transferred from agar slants. However, it would appear from the present work that the adaptation of this organism to gronth with arabinose might easily impose limitations upon its use for assay purposes of sugar mixtures tlcrived from natural materials. A3IINO ACID CONTENTS
TABLE I.
PERFORMASCE OF TEASTS IS STILLAGE
Gro\rth
Period,
\-east
llr.
Ilycotoruln
0 21 48
tiaiisenula
0 24 48
__ Yeaat I-ield
Re
