A PINK YEAST CAUSING SPOILAGE IN OYSTERS. 13 



ALCOHOL, ALDEHYDE, AND ACETONE PRODUCTION. 



The production of alcohol in sugar solutions is without doubt the 

 best known of all properties of the yeast plant. Alcoholic fermenta- 

 tions due to the growth of fungi have been known for a long time, 

 and it was because of the alcoholic fermentation of sugars that the 

 true yeasts were given the name Saccharomycetes. One of the dis- 

 tinguishing features of the TorulaB or pseudo yeasts, however, is the 

 fact that they cause alcoholic fermentation to a very slight degree or 

 not at all. In studying the pink yeast, experiments were conducted 

 to determine whether or not this organism produces alcohol in various 

 sugar media. 



The pink yeast was grown at room temperature in dextrose, levu- 

 lose, maltose, lactose, galactose, raffinose, arabinose, saccharose, gly- 

 cogen, inulin, and dextrin broths for 72 hours with controls. At the 

 end of the incubation period the cultures and controls were attached 

 to a condenser and distilled. The distillate was tested for alcohol, 

 aldehyde, and acetone by routine methods, and no positive results 

 were obtained. Applied to a culture of a known alcohol-producing 

 yeast these methods gave positive tests. The pink yeast does not give 

 the test for alcohol, aldehyde, or acetone when grown under the con- 

 ditions described, but whether small amounts of these compounds 

 may be formed under other conditions was not determined. 



GAS PRODUCTION. 



Experiments were also conducted to determine the gas production 

 of the pink yeast. Dextrose, maltose, lactose, raffinose, saccharose, 

 and glycogen broths were prepared as described. Fifteen cubic centi- 

 meters of each medium were used in Dunham fermentation tubes. 

 After inoculating with the pink yeast the tubes were incubated, with 

 controls, at room temperature, and for 7 days examined for the pro- 

 duction of gas. Cultures were also grown anaerobically under 

 paraffin oil. 



In none of the tubes was any gas produced in 7 days. The tubes 

 were reserved for the examination at a later period, and no gas pro- 

 duction was observed for 21 days. 



ENZYME PRODUCTION. 



Enzyme production is a property possessed by many yeasts. Most 

 of the true yeasts produce invertase, which inverts saccharose to 

 dextrose and levulose. Certain yeasts also produce protease and 

 diastase. Experiments were conducted to determine whether or not 

 protease, diastase, invertase, or rennin are produced by the pink 

 yeast. 



