.MILK FERMENTATIONS 



6T 



Milk . . . 



Dextrose broth 

 Lactose broth 



Saccharose broth 



Nitrate broth 

 Peptone broth . 



Relation to 

 oxygen 



f Coagulation 

 . -j Degree of reaction 

 [ Casein liquefaction 



/Gas 



' t Acid 



| Gas 



Ft Acid 

 i. Biochemical Saccharose broth | A " d 

 reactions 

 Nitrite formation 



Indol production 



f Aerobic 



I\ Facultative anaerobic 

 oxygen . . i 

 [_ Anaerobic 

 Relation to tern- f Growth at 20 C. 

 perature . . \ Growth at 37 C. 

 Thermal death point below 80 C. 



The morphological study should be made on fully devel- 

 oped cultures. Cultures which are growing rapidly may pre- 

 sent a large number of immature forms. Old cultures may 

 .contain degenerated and altered forms (involution types). No 

 definite statement can be made in regard to the age of a cul- 

 ture, but, as a rule, those grown at 37 C. should not be 

 over twenty-four to forty-eight hours old, and those grown 

 at 20 C. from forty-eight to seventy-two hours old. Exam- 

 inations of material should be made from both solid and 

 liquid media in both stained and unstained preparations. 



In Appendix B is given the scheme for the detailed study 

 of an organism, recommended by the Society of American Bac- 

 teriologists, together with a glossary of the terms employed 

 in describing the cultural characteristics of an organism. 



Action on carbohydrates. The ability of the bacteria to 

 ferment sugar with the production of gas and acid is best 

 determined by the use of the fermentation tube, since this 



