UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 782 
Contribution from the Bureau of Animal Industry • 
JOHN R. MOHLER, Chief 
Washington, D. C. 
PROFESSIONAL PAPER 
June 17, 1919 
A STUDY OF THE ALKALI-FORMING 
BACTERIA FOUND IN MILK 
By 
S. HENRY AYERS, PHILIP RUPP, and WM. T. JOHNSON, Jr., 
of the Dairy Division, Bureau of Animal Industry 
CONTENTS 
Pag6 
Historical Review 1 
Definition of the Alkali-Forming Groups 
of Bacteria 2 
Cause of the Alkaline Reaction in Milk . 3 
Sources of the Alkali-Forming Bacteria . 9 
Morphology and Growth 10 
Sources of Nitrogen ........ 11 
Fermentation of Carbohydrates . . . . 
Fermentation of Alcohols 
Fermentation of Salts of Organic Acids . 
Reduction of Nitrates and Nitrites . . 
Arbitrary Grouping of Alkali-Forming 
Bacteria From Milk ....... 
Summary and Conclusions . . . . . 
Page 
12 
17 
19 
35 
WASHINGTON 
GOVERNMENT PRINTING OFFICE 
1919 
