WHITE AND ORANGE STAPHYLOCOCCI 151 



FERMENTATION OF CARBOHYDRATE MEDIA 



In view of the comparatvely slight difference in gelatinolytic 

 power between the white and orange cocci, it seemed important 

 to study as many other biochemical properties as possible in 

 order to determine whether the two chromogenic types were 

 really deserving of generic rank; and in view of the important 

 light thrown by the study of fermentative reactions upon the 

 systematic relationships of the colon-typhoid group we have 

 devoted considerable attention to this point. Very little previous 

 work has been done on the power of the staphylococci to ferment 

 various carbohydrate media. It is well known of course that 

 they usually attack the more familiar sugars with the formation 

 of acid, but no gas. Gordon (1906) studied the action of the 

 white staphylococci on lactose, maltose, glycerol and mannitol. 

 Dudgeon (1908) used a considerable series of carbohydrates but 

 his work was not quantitative. The Winslows studied glucose 

 and lactose only while Kligler (1913) added sucrose. In both 

 cases generally positive results were reported. 



In our own study we have used not only glucose, lactose and 

 sucrose but also maltose, rafhnose, mannitol, dulcitol, salicin 

 and inulin. Two different media were employed in this study, 

 the dehydrated bacto nutrient broth prepared by the Digestive 

 Ferments Company and the peptone medium of Clark and Lubs. 



The dehydrated medium contained 3 parts of bacto beef 

 extract and 5 parts of bacto peptone and when dissolved (8 grams 

 to a liter of distilled water) and sterilized for twenty minutes at 

 15 pounds, it had a pH value between 6.7 and 6.8. The peptone 

 medium contained 0.5 per cent K 2 HP0 4 and 0.5 per cent Witte's 

 peptone; and was adjusted to a pH value of 7.4. 



To each medium was added 2.7 per cent of a 0.04 per cent 

 alcoholic solution of bromcresol purple before sterilization (as 

 suggested by Bronfenbrenner, 1918) and 0.5 per cent of sterile 

 carbohydrate after sterilization. The pH value was determined 

 after 1, 3, 5 and 7 days of incubation at 30°C. by matching the 

 tubes against the standards of Clark and Lubs (1917). 



