QUALITATIVE CATABOLIC REACTIONS OF BACTERIA 75 
1. CeHnOe = 2CH3.CH2.OH + 2C02. Alcoholic fermentation. 
Glucose Alcohol. 
2. C6H12O6 = 2CH3.CHOH.COOH. Lactic acid fermentation. 
Glucose. Lactic acid. 
3. CeHisOe = 3CH3.COOH. Acetic acid fermentation. 
Glucose. Acetic acid. 
4. CeHisOe = CH3.CH2.CH2.COOH + 2CO2 + 2H2. Butyric acid fermentation. 
Glucose. Butyric acid. 
Xow it is realized that these various types of fermentation are much 
more complex, and while it is freely admitted that there are yet details 
to be worked out, the general character of the reaction is fairly well 
kno^^^l in each instance. 
The work of Frankland and his associates, of Harden, and recently 
the highly important studies of Xeuberg and his associates, has cleared 
up many of the important details and revealed the remarkable complex- 
ity of fermentation processes. In spite of this complexity, however, 
there seems to be an underlying similarity of pattern in these fermenta- 
tions which in the light of current information must be regarded as 
significant. 
The Neuberg equations together with the Frankland-Frew^-Harden 
equations have made it possible not only to strike a fairly accurate 
balance sheet of the lactic acid fermentations but also to have an insight 
into the mechanism of the process. 
Xeuberg, by means of his aldehyde-fixing reaction (abfangverfahren^) 
and his "Dismutation procedure,'"- the former utilizing sodium sulphite 
in alkaline medium, the latter by alkali alone, has isolated the principal 
intermediary products in the lactic acid fermentation, and has shown, 
furthermore, how the removal of certain of these intermediary products 
from further change may alter the kind and amount of the final products 
of fermentation. 
Equation I. 
C6H12O6 + Na2S03 = CsHsOs + CHa.CHO.NaHSOs + NaHCOs 
Glucose. Glycerol. Acetaldehyde-sulphate compound. 
Upon acidifying, this becomes: CsHnOg + CH3CHO + CO 2. 
Equation II. 
(a) C6H12O6 = CH3.CHOH.COOH + CH3.CO.COOH + H2 
Glucose. Lactic acid. Pyruvic acid. 
(6) 2CH3.CO.COOH (carboxylase) = 2CH3.CHO + 2CO2 
Acetaldehyde. 
(c) 2CH3.CHO + H2O (Cannizzaro reaction) = CH3.COOH + C2H5OH 
Acetic acid. Alcohol. 
The complete equation therefore, is: 
2C6H12O6 + H2O = 2cH3.CHOH.COOH + CH3.COOH + C2H8OH + 2H2 + 2CO2. 
1 Neuberg and Kobel: Handb. d. biol. Arbeitsmeth., 1927, abt. iv, 1, 593. 
= Neuberg and Hirsch: Biochem. Ztschr., 1919, 100, 304. 
