QUALITATIVE CATABOLIC REACTIONS OF BACTERIA 73 
pionic acid) for energy, first eliminating the nitrogen (deamination), 
then oxidizing the carbon. The indol radical which is left is not a 
source of energy; it cannot be oxidized by these organisms, conse- 
ciiiently it remains as such in culture media or is absorbed from the 
intestinal tract. 
2. Production of phenolic bodies from tyrosine.^ 
Phenol is not oxidizable by bacteria, hence it remains as such 
unchanged in the culture media. Phenol (or cresol) may be absorbed 
from the intestinal tract, but it appears eventually in the urine as an 
ethereal sulphate, precisely as indol appears in the urine as indican. 
Indol and phenolic bodies are not found in cultures containing utiliz- 
able carbohydrate— the bacteria which produce indol and phenols 
from tryptophane and tyrosine, respectively, can obtain their requisite 
energy far more directly and economically from the sugar than from 
the nitrogen-containing amino-acid.^ Doubtless the same general 
principle applies to the formation of these aromatic substances in 
the intestinal tract. 
3. Formation of amines from amino-acids by bacterial action. These 
reactions, so far as available information shows, occur only in media 
containing carbohydrates. The decarboxylization is apparently due 
to an enzyme much like Neuberg's carboxylase. (See p. 71.) 
(a) Cadaverin from lysine.^ 
CH2.CH2.CH2.CH2.CH.COOH CH2.CH2.CH2.CH2.CH2 
I I I I + CO. 
NH2 NH2 -^ NH2 NH2 
Lysine. Cadaverin. 
(6) Putrescin from ornithin.^ 
CH2.CH2.CH2.CH.coOH CH2.CH2.CH2.CH2 
I i I I + CO2 
NH2 NH2 NH2 NH2 
Ornithin. Putrescin. 
(c) Betaimidazoleethylamine from histidine.^ 
H— C— NH\ H— C— NH\ 
II CH II CH 
C— N / C— N / + CO2 
CH2 CH2 
I I 
CHNH2 -^ CH2NH2 
I 
COOH 
Histidine. Betaimidazoleethylamine. 
' Baumann: Ber. d. deutach. chem. Gesell., 1877, 10, 685. 
2 Hanke and Koessler (Jour. Biol. Chem., 1924, 59, 855) have shown that phenol is 
produced by certain strains of B. coU, but only in media having an alkaline reaction. 
3 Ladenburg: Ber. d. deutsch. chem. Gesell., 1887, 20, 2216. 
4 Ellinger: Ztschr. f. physiol. Chem., 1902, 29, 334; Ber. d. deut.sch. chem. Gesell., 
1899, 31, 3183; ibid., 1900, 32, 3542. 
5 See Barger and Dakin: Biochem. Jour., 1916, 10, 378. Bostock: Ibid., 1911- 
1912, 6, 53. 
