508 



STATE BOARD OF AGRICU1.TURB,. 



Experiment V. 



Having reached such definite conclusions with regard to the germicidal 

 power or inhibitive effect of the acid produced by these different lactic 

 organisms in lactose broth, it becomes necessary to establish a relation- 

 ship between lactose broth, and milk wdth reference to the relative amount 

 of lactic acid which may be produced by these different lactic organisms 

 in the different media. Whey was compared relatively with lactose broth 

 and milk. 



The following data, establishing the above, concludes this series of 

 experiments : 



TABLE XXVII. 



-Relative Acidity Produced by Lactic Organisms in 5 per cent Lactose 

 Broth, Whey and Ordinary Milk. 



Bad. bulgaricum. 



Age of lactic 

 culture. 



4 days 



7 days 



10 days 



13 days 



4 days 



7 days 



10 days 



13 days 



4 days 



7 days 



10 days 



4 days 



7 days 



10 days 



4 days 



7 days 



10 days 



4 days 



7 days 



10 days 



Media. 



Milk. 



281° 

 299° 

 309° 

 310° 



291° 

 309° 

 321° 

 321° 



218° 

 314° 

 318° 



315° 

 318° 

 328° 



299° 

 310° 

 310° 



303° 

 312° 

 318° 



Broth 



*2G° 

 115° 

 117° 

 117° 



*26° 

 107° 

 104° 

 107° 



76° 

 82° 

 88° 



50° 

 56° 

 60° 



42° 

 45° 

 62° 



51° 



61° 

 102° 



^Tiey 



82° 

 87° 

 88° 

 87° 



83° 

 83° 

 84° 

 89° 



100° 

 103° 

 109° 



98° 

 104° 

 108° 



94° 



99° 



104° 



99° 

 101° 

 106° 



Bad. ladis acidi (from sour milk). 



Age of lactic 

 culture. 



4 days 



7 days 



10 days 



13 days 



4 days 



7 days 



10 days 



13 days 



4 days 



7 days 



10 days 



4 days 



7 days 



10 days 



4 days 



7 days 



10 days 



4 days 



7 days 



10 days 



Media. 



Milk. 



105° 

 114° 

 111° 

 113° 



112° 

 113° 

 108° 

 101° 



112° 

 113° 

 112° 



114° 

 119° 

 119° 



114° 

 116° 

 115° 



115° 

 116° 

 117° 



Broth, 



55° 

 53° 

 53° 

 53° 



52° 

 53° 

 54° 

 54° 



48° 

 49° 

 52° 



49° 

 **» 



50° 

 50° 



48° 

 51° 

 53° 



Whey. 



39° 

 37° 

 37° 

 35° 



37° 

 38° 

 39° 

 39° 



41° 

 41° 

 41° 



3?° 

 39° 

 39° 



44° 



42° 

 44° 



38° 

 41° 

 43° 



Bad. ladis acidi, No. 4. 



Age of lactic 

 culture. 



4 days. 



7 days. 



10 days. 



4 days. 



7 days. 



10 days. 



4 days. 



7 days. 



10 days. 



4 days. 



7 days. 



10 days. 



4 days. 



7 days. 



10 days. 



4 days. 



7 days. 



10 days. 



Media. 



Milk. 



82° 

 87° 



70° 

 83= 



Broth. 



51° 

 55° 

 53° 



49° 

 52° 



87° 54° 



69° 

 86° 

 86° 



**83° 

 91° 

 97° 



**80° 

 89° 

 90° 



**81° 

 94° 

 95° 



52° 

 52° 



*** 



51° 



52° 

 *** 



49° 

 52° 

 53° 



50° 

 51° 

 52° 



Whey. 



30° 

 31° 

 31° 



31° 



32° 

 32° 



32° 

 34° 

 34° 



34° 

 35° 

 35° 



32° 

 35° 

 35° 



35° 

 33° 

 34° 



*Bad. bulgaricum was grown in old broth that was slightly concentrated (18°+). This may have caused the exceptionally 

 high acidity. ' 



Q'lie first four days the culture was kept at 21° which accounts for the low acidity at *. Afterwards these and the remaining 

 cultures of this organism were kept at 37°C. The temperature seemed to have a marked cfieet on the production of acid in the 

 whey cultures. 



**Milk was used in these tests in which the lactose had been inverted in the process of sterilization. It has been observed that 

 superheated milk (brownish in color), registers an amount of acid appreciably greater than tliat in unhealed or in properly heated 

 sterilized milk. 



♦♦♦Contaminated with molds. Cultures discarded. 



The following table gives the average of Table XXVII with, the corre 

 sponding percentages of acid produced in the different media. 



From this table the amount of acid required for destroying B. typhosus 

 in milk mav be theoreticallv estimated. 



