SOME CHARACTERS WHICH DIFFERENTIATE THE 

 LACTIC-ACID STREPTOCOCCUS FROM STREPTO- 

 COCCI OF THE PYOGENES TYPE OCCURRING 



IN MILK 



J. M. SHERMAN and W. R. ALBUS 



From 'the Bacteriological Laboratories of The Pennsylvania State College and 

 Agricultural Experiment Station, State College, Pennsylvania 



Received for publication March 2, 1917 

 INTRODUCTION 



Much confusion exists in bacteriological literature concerning 

 the identity of the lactic-acid streptococcus and its relation to 

 the other chain-forming cocci which occur in milk. It is gen- 

 erally considered that the true lactic-acid bacteria (variously 

 known as Bad. lactis-acidi, Streptococcus lacticus, B. lactici- 

 acidi, Bacterium or Streptococcus guntheri, etc.) comprise a 

 definite and rather well defined group of organisms. But no 

 sharp points of distinction have been established between these 

 organisms and other streptococci, notably the pyogenic strep- 

 tococci, which are usually, if not always, to be found in market 

 milk. 



The descriptions given for the lactic-acid streptococcus in the 

 older publications on systematic bacteriology, such as the books 

 by Migula (1900) and Chester (1901), could be applied equally 

 well to the pathogenic streptococci. The same confusion is 

 found in the more recent literature. Weigmann (1911) includes 

 the streptococcus of bovine mammitis in the same group as the 

 true lactic-acid organism. Ernst (1914) says that there is no 

 known method by which the lactic-acid streptococcus and the 

 mammitis streptococcus can be differentiated. Jordan (1915) 

 states that ''the milk streptococcus in all its properties is extra- 

 ordinarily like Streptococcus pyogenes." Heinemann (1906) who 

 has extensively studied the lactic-acid bacteria, concludes that 



153 



