ALKALI-FORMING BACTERIA FOUND IN MILK. 



13 



consequently this alkali formation would interfere with the reaction 

 as a means for determining the dextrose fermentation. 



Table 4. — Reaction ^produced by the alhali-forming bacteria in dextrose and plain-extract 



broth. 



Culture No. 



Dextrose-extract 

 broth. 



7 days. 21 days 



7?.. 

 101. 

 102. 

 103. 

 104. 



105. 

 106. 

 107. 

 108. 

 111. 



112. 

 113. 

 114. 

 116. 

 117. 



118. 

 119. 

 120. 

 121. 

 122. 



123. 

 124. 

 125. 

 126. 



C.c. 

 + 2.40 

 + .66 



- .04 

 + 2.40 

 + 1.60 



-1.00 



- .64 



- .94 



- .90 



- .06 



- .60 



- .94 



- .88 



- .58 



+ 1.10 



- .74 



+3.00 



+2.08 



- .80 



- .82 



- .50 



- .90 



- .80 

 + 1.94 



2+5.60 



- .70 



+ 1.86 



- .86 



- .64 



- .64 



C.c. 

 + 1.46 

 + 1.40 

 + .82 



+ .78 



- .70 



- .20 



- .74 



- .84 



- .90 



+2.46 



- .80 



- .90 



+ .76 

 + 1.58 



- .82 



- .76 



- .82 

 + .42 

 2+4.46 



+ 1.70 



- .90 



- .80 



Beef- 

 extract 



broth, 

 14 days. 



C.c. 

 -0.39 



- .43 



- .29 



- .41 



- .37 



- .38 



- .40 



- .36 



- .30 



- .30 



- .30 



- .29 



- .30 



- .2.S 



- .38 



- .32 



- .42 



- .41 



- .41 



- .40 



- .49 



- .40 



- .29 



- .31 



- .39 



- .35 



- .39 



- .42 



- .28 



- .38 



- .37 



- .32 



- .34 



- .34 



Culture No. 



128. 

 130. 

 131. 

 132. 

 133. 



134. 

 135. 

 136. 

 137. 

 138. 



139. 

 140. 

 141. 

 142. 

 143. 



144. 

 145. 

 146. 

 147. 

 303. 



309. 

 314. 

 317. 

 319. 

 321. 



322. 

 325. 

 326. 

 340. 

 353.. 



354. 

 356. 

 361. 

 362. 



Dextrose-extract 

 broth. 



7 days. 21 



C.c 



+ 1.40 



- .84 



- .56 



- .76 

 2+5.36 



2+4.44 



- .88 



- .76 

 + 1.12 



-1.00 

 + 2.56 



- .80 

 + .93 



- .60 



- .50 



- .84 

 -1.00 



- .72 



- .26 



- .20 



- .52 



+ 1.54 



- .44 



- .30 



- .50 



- .40 



- .90 



- .70 



- .84 



- .50 



- .16 



- .40 



C.c. 

 -0.86 



- .92 



- .90 



- .82 

 2+2. 72 



2+4. 76 



- .92 



- .82 



+2.88 



+ .76 

 - .86 

 + .44 



Beef- 

 extract 



broth, 

 14 days. 



.88 

 .76 



+ .94 



- .76 



- .48 



- .20 



+1.66 



- .16 



- .32 



- .70 



- .52 



"-'."34' 



C.c. 

 -0.37 



- .39 



- .38 



- .32 

 2- .40 



2- .35 



- .39 



- .37 



- .39 



- .32 



- .42 



- .29 



- .62 



- .25 



- .33 



- .34 



- .39 



- .39 



- .32 



- .32 



- .23 



- .47 



- .32 



Minus (—) signs indicate an altaline change i in titration. 

 Plus (+ ) signs indicate an acid change in titration. 



1 Change from control, in c. c. N/10 NaOH titrating 10 c. c. of medium. 



2 Produced gas. 



In order to avoid the complicating alkaline fermentation in extract 

 broth, synthetic media were prepared which consisted of sodium- 

 ammonium phosphate as the only source of nitrogen with dextrose 

 as the only source of carbon. The media used had the following 

 composition ; 



Medium A. Medium B. Medium C. 



Sodium-ammonium phosphate grams. . 2. , 1. 5 1. 



Dextrose j do 10.0 3.0 10. 



Potassium chlorid do .1 .1 .2 



Distilled water cubic centimeter . . 1,000 1,000 1,000 



The results of the fermentation of the dextrose in these media 

 are shown in Table 5. The change in the hydrogen-ion concentra- 

 tion during 14 days' incubation was used as a measure of thefermenta- 



