A PINK YEAST CAUSING SPOILAGE IN OYSTERS. 



15 



The results in the table indicate that no proteolytic, diastatic, nor 

 milk-coagulating enzyme is formed by the pink yeast, but that the 

 yeast does produce invertase which changes saccharose to dextrose 

 and levulose. 



INDOLE PRODUCTION. 



In order to test for the production of indole by the pink yeast, cul- 

 tures were grown for 15 clays in tryptophane broth at room tempera- 

 ture, with controls, and were tested daily. The tests were made with 

 paradimethylaminobenzaldehyde and hydrochloric acid. No posi- 

 tive tests were obtained. 



AMMONIA PRODUCTION. 



The power of the pink yeast to reduce nitrates to nitrites and am- 

 monia was tested. The yeast was grown in peptone-nitrate solution 

 for 10 days, and from the fifth to the tenth day the cultures and con- 

 trols were tested for the presence of nitrites and ammonia. Sul- 

 phanilic acid and a-naphthylamin were used in testing for nitrates, 

 while Nessler's reagent was added to the cultures in testing for 

 ammonia. 



Table 5. — Production of nitrites and ammonia. 





Result. 



Organism. 



6 days. 



7 days. 



8 days. 



9 days. 



10 days. 





Ni- 

 trites. 



Am- 

 monia. 



Ni- 

 trites. 



Am- 

 monia. 



Ni- 

 trites. 



Am- 

 monia. 



Ni- 

 trites. 



Am- 

 monia. 



Ni- 

 trites. 



Am- 

 monia. 





+ » 



+ 

 



+ 

 



+ 

 



+ 

 



+ 

 



+ 

 



+ 

 



+ 

 



+ 



Control 







The results of the experiments show that the nitrates in the cul- 

 ture medium are reduced to nitrites and ammonia. 



PHENOL PRODUCTION. 



Cultures were prepared in nutrient broth in flasks containing at 

 least 50 cc. of medium, and were incubated at room temperature for 

 3 days with controls. At the end of the 3 days 5 cc. of 25 per cent 

 sulphuric acid were added to the culture, and the mixture was dis- 

 tilled. The distillate was tested with Millon's reagent, ferric chlorid 

 solution, and bromin water. Both the test and control cultures gave 

 no indication of phenol. 



PIGMENT PRODUCTION. 



When grown under favorable conditions, the yeast produces abun- 

 dant pink pigment. The most abundant pigment production is ob- 

 tained when the yeast is grown upon solid sugar media at room tem- 

 perature. The pigment is also produced in liquid media, but in much 



