242 JOHN T. MYERS 



Effect of the variety of commercial peptone, and of the presence of 

 glucose and sucrose on hydrogen sulphide formation 



The hydrogen sulphide producing power of a number of 

 common bacteria was studied in several media. Witte's peptone, 

 "Difco" peptone made by the Digestive Ferments Company, 

 and Fairchild peptone were compared. Four different media 

 were prepared from each brand of peptone, a 3 per cent solution 

 of the peptone containing 0.5 per cent of NaCl, a 3 per cent 

 solution of the peptone containing 0.5 per cent NaCl and 0.5 

 per cent glucose, a 3 per cent solution of the peptone containing 

 0.5 per cent NaCl and 0.5 per cent sucrose, and standard 

 nutrient broth. Glucose and sucrose were chosen because 

 Seifert (1909) reports that glucose decreases and sucrose increases 

 hydrogen sulphide formation by B. paratyphosus B. Table 4 

 summarizes the results. 



Witte's peptone was the most favorable of the three brands 

 in regard to hydrogen sulphide formation, and Fairchild's was 

 more favorable than Difco. Variable amounts of hydrogen 

 sulphide were formed in Witte and not in Difco peptone media 

 by Sarcina lutea, Staphylococcus albus, Staphylococcus aureus, 

 B. prodigiosus, B. pyocyaneus, Mic. tetragenus, a laboratory 

 strain of streptococcus, B. cloacae, B. subtilis, B. anthracis, B. 

 avisepticus, B. bovisepticus, Sp. metchnikovii, Sp. cholerae, B. lactis- 

 aerogenes, and B. mucosus-capsulatus. Larger amounts of hydro- 

 gen sulphide were formed in Witte than in Difco peptone by 

 some of the other organisms. 



Hydrogen sulphide was produced in Fairchild and not in 

 Difco media by B. lactis aerogenes and B. cloacae. It seemed to 

 make no difference which of the four media prepared from each 

 peptone was used. Ordinary broth was as good as any. Glucose 

 and sucrose did not influence the rate or amount of hydrogen 

 sulphide formation. 



It was a striking fact that many species of bacteria produced 

 hydrogen sulphide from Witte's peptone and not from the 

 American brands. This was of course due to difference in 

 chemical constituents. Witte's peptone contains more amino 



