scholarly journals THE USE OF THE FINAL HYDROGEN ION CONCENTRATION IN DIFFERENTIATION OF STREPTOCOCCUS HÆMOLYTICUS OF HUMAN AND BOVINE TYPES

1919 ◽  
Vol 29 (2) ◽  
pp. 215-234 ◽  
Author(s):  
Oswald T. Avery ◽  
Glenn E. Cullen
Keyword(s):  
Hydrogen Ion ◽  
Ion Concentration ◽  
Human Origin ◽  
Practical Application ◽  
Cream Cheese ◽  
Hydrogen Ion Concentration ◽  
Human Type

1. Under the conditions of these experiments, there appears to be a distinct and constant difference in the final hydrogen ion concentration of Streptococcus hæmolyticus from human and bovine sources. 2. Of 124 strains of Streptococcus hæmolyticus from known human origin, 116 reached a final hydrogen ion concentration of from pH 5.0 to 5.3. Only 8 reached a pH more acid than 5.0 and none more acid than pH 4.8. 3. Of 45 strains of Streptococcus hæmolyticus from bovine sources, including 26 strains isolated from milk and the udder of cows, and 19 from cream cheese, 40 reached a final hydrogen ion concentration of pH 4.3 to 4.5. Of the remaining 5 which reached a pH of 5.0 to 5.2, two were of known human type and three of uncertain diagnosis. 4. A rapid and practical application of this method is proposed as a presumptive test in the differentiation of human and bovine types of Streptococcus hæmolyticus.

scholarly journals INFLUENCE OF TEMPERATURE AND HYDROGEN ION CONCENTRATION UPON THE SPORE CYCLE OF BACILLUS SUBTILIS

1919 ◽  
Vol 1 (4) ◽  
pp. 421-428 ◽  
Author(s):  
Arao Itano ◽  
James Neill
Keyword(s):  
Ph Value ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Practical Application ◽  
Vegetative Cells ◽  
Hydrogen Ion Concentration ◽  
Influence Of Temperature ◽  
Ph Values ◽  
Metabolic Products ◽  
Slight Growth

1. At 5°C. no germination took place. 2. At 25°C. and at 37°C. germination occurs if the hydrogen ion concentration of the broth is kept between pH 5 and pH 10, but not at higher or lower pH values. 3. The completion of the spore cycle likewise requires a hydrogen ion concentration between pH 5 and pH 10. 4. The spores can germinate when the pH value is 10, although after germination the vegetative cells multiply only to a very slight extent and soon pass into spores. 5. The slight growth and multiplication of vegetative cells in broth of pH 10 suggest that the formation of endospores in this medium must be caused largely by the unfavorable reaction of the medium rather than by the accumulation of metabolic products. 6. Automatic adjustment of the medium seems to play a rôle in the completion of the spore cycle. 7. The results are not only of theoretical importance but they have a practical application to the preservation of food by canning and by other methods.

Sign in / Sign up

Export Citation Format

Share Document