GROWTH AND FERMENTATIVE CAPACITY 14-5 



data. Only twelve viable cultures were obtained from ninety -four 

 spores originating from single ascospore cultures. In contrast, 

 thirty-five cultures were obtained from seventy-one ascospores 

 isolated from cultures arising from self -fertilized asci. 



One of the self -fertilized asci from culture Db5h (Db5h5b) pro- 

 duced viable 4-spored asci and was carried into the fourth genera- 

 tion. Culture Db512a also produced viable 4-spored asci and was 

 propagated into the fourth generation. 



In the pedigree of the "D" family, viable 4-spored asci were 

 usually obtained from self -fertilized intact asci, and such cultures 

 were generally more vigorous in both yield and ascospore viability 

 than cultures from single ascospores. On this basis, it is possible 

 to distinguish yeast cultures arising from single ascospores and 

 those arising from intact asci. 



A survey of forty cultures of apparently diploid baking yeasts 

 revealed that 24 of them sporulated poorly and produced no 4- 

 spored asci, suggesting that they were illegitimate diploids. Six- 

 teen of them sporulated abundantly and produced 4-spored asci, 

 suggesting that they were legitimate diploids. 



VARIATION IN GROWTH AND GAS PRODUCTION 



Cultures from various pedigreed sources totalling over 1450 

 genetically different strains were studied by Lindegren, Spiegel- 

 man, and Lindegren (1945) with regard to the volume (crop or yield) 

 of cells produced in 10 cc. of peptone, yeast-extract, sugar medium 

 and the ability to produce COq from various sugars. The progenies 

 from 12 strains of bakers' yeasts were examined. The progenies of 

 only six of the strains will be considered here in detail. They are re- 

 presentative of the range of biochemical heterogeneity found in the 

 fermentative characteristics in all twelve. As will be indicated at 

 the proper point, some of the studies reported here were made on 

 random sample strains obtained from all 12 pedigrees. The 12 dip- 

 loid sporulating yeasts, symbolized by letters (G, M, FD, F, D, L, 

 BE, HD), stem from commercial baking yeasts collected on the 

 market, whereas strains 800, 801, 806, 812 were obtained from the 

 yeast collection of the Northern Regional Research Laboratory at 

 Peoria, Illinois, through the courtesy of Dr. L. J. Wickerham. 



The medium in which the cells were grown consisted of 0.5 per 

 cent peptone, M/15 phosphate buffer adjusted to pH 6.4, and 2 cc. 

 of liquid yeast extract per liter. Carbohydrate was added to the 

 above to make a 2 per cent solution. In the medium labelled "3 -sugar 

 broth," dextrose, sucrose, and maltose were used in a ratio of 

 2:1:1, Results obtained on single sugars are labelled in the fig- 

 ures with the name of the sugar used. Yield and gas evolution char- 

 acteristics were examined on sucrose, glucose, and galactose, levu- 

 lose and maltose. 



