A PINK YEAST CAUSING SPOILAGE IN OYSTERS. 6 



budding fungus in which he claims to have observed sporulation, 

 but J. Chr. Bay (1896) disputed this in a subsequent publication. 



Although frequent mention has been made in various trade jour- 

 nals of the occurrence of the pink color in oysters, no detailed study 

 of the relation of the pink yeast to the oyster industry has been 

 published thus far. Bates and Round have submitted to the Bu- 

 reau of Chemistry a preliminary report on the occurrence of a pink 

 yeast in oysters during the fall of 1914. Based upon their report, 

 a statement was made in the Report of the Chemist 1 that . " It was- 

 discovered that a yeast was the probable cause of the reddening 

 which affected thousands of gallons of oysters during the past 

 season.*' 



From the foregoing paragraphs it is evident that these pink 

 yeasts are widely distributed in nature. Owing to a lack of ade- 

 quate description of these forms, no attempt has been made to iden- 

 tify the organism reported here with any of the forms mentioned 

 other than that they all belong to the same large group of Torulse. 



DISTRIBUTION OF THE PINK YEAST. 



After the cause of the color had been found to be a pink yeast the 

 next thing undertaken was a study of the distribution of the organ- 

 ism in the oyster house, in oysters, in surface and deep water sam- 

 ples from Narragansett Bay, and in mud samples taken from the 

 oyster beds. If the distribution was limited to the house, the solu- 

 tion of the problem was simple, consisting merely of finding some 

 suitable method of removing the infection from everything with 

 which the oysters came in contact. If, on the other hand, the habitat 

 of the yeast extended to the water and mud on the oyster grounds, 

 the problem became more complex, with less prospect of eliminating 

 the trouble. An examination was first made of the oyster house and 

 of the utensils in and about the house. Later oysters taken from the 

 decks of the boats were examined before they had entered the house, 

 and finally numerous samples of water and mud were analyzed for 

 the presence of the yeast. 



Culture media. — After several preliminary experiments with spe- 

 cial culture media of various kinds it was decided that satisfactory 

 results would be obtained with dextrose agar and dextrose broth. 

 These media, upon which the yeast grows abundantly, have been 

 used throughout the work. The agar and broth were prepared ac- 

 cording to the directions given in the Standard Methods of Water 

 Analysis of the American Public Health Association. Beef extract, 

 peptone, and pure dextrose were used, and the reaction was adjusted 

 to -\-0.5 Fuller's scale. One per cent of dextrose has been found 

 sufficient. 



1 U. S. Dept. Agr. An. Repts., 1915. 



