ALKALI-FORMING BACTERIA FOUND IN MILK. 
17 
Table 8. — The cultures which fermented lactose in synthetic media and the milk reactions 
by titration of the same cultures. 
Lactose synthetic 
media. 
Reaction of milk 1 cultures 
after— 
A. 
C. 
7 days. 
14 days. 
30 days. 
Ph. 
6.9 
Ph. 
6.8 
C.c. 
22.0 
C.c. 
22.0 
C.c. 
22.0 
10 
6.7 
6.7 
6.7 
6.7 
6.7 
6.7 
6.6 
6.7 
6.6 
6.7 
6.7 
6.1 
6.1 
6.1 
4.8 
6.4 
6.4 
6.4 
6.0 
5.9 
6.3 
6.1 
2.0 
2.8 
4.6 
10.2 
5.6 
3.0 
5.2 
5.2 
15.0 
13.0 
5.4 
10.6 
7.4 
7.0 
21.0 
6.6 
7.8 
2.8 
9.6 
13.6 
7.2 
6.8 
17.0 
12 
15.4 
49 
12.8 
107 
45.2 
112 
10.2 
113 
15.8 
120 
8.4 
123 
19.0 
137 
39.6 
141 
17.8 
143 
16.2 
i 100 c. c. of milk titrated with tenth-normal NaOH. 
In the study of the fermentation of sugars by the alkali-forming 
bacteria care must be exercised to use a medium in which organic- 
acid salts are not present, for they are readily oxidized to alkaline 
carbonates, which may mask an acid fermentation of the sugar. 
A synthetic medium is of the greatest assistance in this connection. 
FERMENTATION OF ALCOHOLS. 
In a study of the fermentation of sugars it is customary to include 
some of the polyatomic alcohols, such as adonite, dulcite, mannite, 
and glycerin. R was found that these polyatomic alcohols were not 
particularly good sources of carbon for the alkali group of organisms 
when used in a synthetic medium composed of sodium-ammonium 
phosphate 2 grams, potassium chlorid 0.1 gram, test alcohol 2 grams, 
and distilled water 1,000 cubic centimeters. None of the cultures 
fermented adonite or dulcite, but, as is shown in Table 9, 5 cultures 
fermented mannite and 3 fermented glycerin. In mannite the maxi- 
mum change in hydrogen-ion concentration was from P H 7.1 (control) 
to P H 6.1 and in glycerin from P H 6.9 (control) to P H 6.4. 
The monoatomic alcohols are not commonly used as test fermenta- 
tion substances, but it was thought advisable to determine whether 
some of them could supply carbon for the alkali-forming bacteria. 
Four of the monoatomic alcohols, namely, methyl, ethyl, propyl^ 
and amyl, were tested with different amounts in the sodium-ammo- 
nium phosphate medium just described. As nothing was known 
regarding the effect of different concentrations of these alcohols on 
the bacteria, 3 different sets of media with 10, 5, and 3 grams, re- 
spectively, of alcohol to the liter were used. The cultures were incu- 
bated 7 days at 30° C. and any change over P H 0.2 in a hydrogen-ion 
104410°— 10— Bull. 782 3 
