ALKALI-FOEMIXG BACTERIA FOUjSTD IjST MILK. 



15 



Only the cultures wMch. showed a slight P^ change in medium A 

 were run in medium C. From the results of the work it was evident 

 that 44 of the 68 cultures of alkali-forming bacteria could ferment 

 dextrose, but many of them to only a slight extent. The fermen- 

 tation was slow with certain of the bacteria, as is seen in Table 6, 

 which shows the Ph value of 3 cultures in medium A. These cultures 

 represent 3 ty|>es of fermentation. Culture 12 reached Pg 4.5 after 

 3 days' hicubation at 30° C, while culture 319 reached P^ 6.0 only 

 after 10 days, and its highest hydrogen-ion concentration was P^ 5.5. 

 Cultm^e 140 reached Pg 6.5 in 10 days, which seemed to be its highest 

 point, and did not show further change after 21 days' incubation. 



Table 6. — Three types of dextrose fermentations as shoicn by the hydrogen-ion concen- 

 tration in terms o/Ph. 



Culture No. 











Days. 











1 



2 



3 



4 



5 



7 



10 



14 



21 



Control 



7.1 



7.0 



7.0 



7.0 



7.0 



7.0 



7.0 



7.0 



6.9 





12 



6.6 

 6.9 

 7.0 



5.6 

 6.8 

 7.0 



4.5 

 6.8 

 7.0 



4.5 

 6.8 

 6.9 



4.5 



6.0 

 6.9 



4.5 

 6.6 



C.S 



4.5 

 6.0 

 6.5 



4.5 

 6 

 6.5 



4.5 



■ 5.5 



6.5 



319 



140 - 





T.-\.BLE 7. — Comparison of the fermentation of dextrose in an extract broth and a synthetic 



medium . 



Culture 

 No. 



Dextrose broth. 



Dex- 

 trose- 



sodium- 

 ammo- 1 

 ninm 

 phos- 

 phate. 



Culture 

 No. 



Dextrose broth. 



Dex- 

 trose- 



sodiiun- 

 ammo- 

 nium 

 phos- 

 phate. 



Culture 

 No. 



Dextrose broth. 



Dex- 



trose- 

 sodium- 

 ammo- 

 nimn 

 phos- 

 phate. 





7 days. 



21 days. 14 days. 



7 days. 21 days. 



14 days. 



7 days. 



21 days. 



14 days. 



10 



12 



31 



49 



59 



60 



61 



62 



66 



72 



73 



101 



102 



103 



104 



105 



106 



107 



108 



Ill 



112 



113 



114 



116.. ->. 

 117 



+ 

 + 



-1- 



+ 

 + 



+ 



+ 

 -f- 

 



0- 







+ 







+ 



-f- 







+ 

 -f 







+ 







-1- 

 -1- 







+ 

 + 



118 



119 



120 



121 



122 



123 



124 



125 



126 



128 



130 



131 



132 



133 



135 



136 



137 



138 



139 



140 



141 



112 



143 



144 



+ 

 + 



4- 

 + 



-1- 

 4- 



-1- 

 4- 



+ 



-1- 



-1- 

 -1- 







+ 

 + 

 -1- 

 



+ 

 + 

 + 

 + 

 







+ 



t 



+ 



+ 

 + 



+ 







+ 



-!- 

 



-1- 



+ 



145 



146 



147 



303 



309 



317 



319 



321 



322 



325 



326 



340 



3.53 



354 



356 



361 



362 



+ 



+ 

 





 + 

 

 

 



+ 







+ 

 + 



4- 



4- - 



4- 







4- 

 4- 



4- 



ilinus ( — ) = alkaUne . 



Plus (+)=acid. 



Zero (0)=no change. 



