Feb. 1,1925 
Decomposition of Proteins and Amino Acids 
265 
(17) and numerous other investigators 
found ammonia formation a good index 
of proteolysis, while DeBord (5) and 
others found that it is not a reliable 
index. The term is merely relative 
and should not be made to mean any 
more than it does. 
When a protein is acted upon by 
microorganisms it is first hydrolyzed 
into various protein derivatives, in¬ 
cluding the amino acids; the latter 
are then deaminized. It is important 
to know whether all constituents of the 
protein molecule are acted upon alike 
by microorganisms, or whether some 
are acted upon first and others after. 
Robinson and Tartar (22) found that 
all the nitrogenous compounds are 
changed more or less by the bacteria 
with the formation of ammonia; in no 
case was one of the derivatives com¬ 
pletely destroyed, but the rapidity of 
action varies with the different pro¬ 
teins. Lathrop (15) pointed out that 
the monoamino and diamino acid ni¬ 
trogen (especially the latter, according 
to Kelley (11) ) are the chief sources, 
in the protein molecule, from which 
ammonia is formed. 
There are available, however, undis¬ 
puted facts in the literature that cer¬ 
tain organisms prefer one chemical 
group to another and that different 
organisms may vary in their prefer¬ 
ences in this respect. Rubner (23, 24) 
demonstrated calorimetrically that bac¬ 
teria consume a great deal more mate¬ 
rial for energy than for growth (increase 
in protoplasm). B. proteus, for exam¬ 
ple, utilized, in a period of 10 days, 3.01 
calories for growth, out of 12.32 calories 
transformed; longer periods of growth 
even increased the ratio of the number 
of calories used for energy to that used 
for growth. Growth and energy con¬ 
sumption are so related that they are 
affected alike by environmental condi¬ 
tions, as temperature. Different spe¬ 
cies, however, were found by Rubner to 
behave differently in this respect. 
The fungi producing an abundant 
growth and assimilating a large amount 
of the available carbon behave differ¬ 
ently in this respect; about half of the 
nutrient consumed is used for resynthe¬ 
sizing the cells (14) l Terroine and 
Wurmser (28, 29) found that Aspergillus 
niger stores in the mycelium as much as 
59.6 per cent of the metabolizable 
energy. It may thus be concluded that, 
as a general rule, bacteria utilize a much 
smaller amount of energy than fungi 
for growth and the synthesis of proto¬ 
plasm. 
As to the decomposition of different 
amino acids and acid amides in the soil, 
which contains a mixture of a large 
number of organisms, Jodidi (10) 
demonstrated that the rate of their 
transformation into ammonia is greatly 
influenced by their chemical structure; 
amino acids and acid amides of equal 
structure were found to yield about the 
same proportion of ammonia. 
According to Blanchetiere (2), ala¬ 
nine, leucine, aspargine, phenylalanine* 
tyrosine, and histidine are readily util¬ 
ized by Bad. fluorescens liquefaciens, as 
sources of both carbon and nitrogen; 
glutamic acid and tryptophane are 
utilized more slowly, and glycocoll only 
after a period of incubation, longer 
than one month. 
EXPERIMENTAL DATA 
A standard medium, synthetic in 
composition, has been used in the 
following investigations; it contains the 
following mineral constituents: 
K 2 HPO 4 ... 1.0 gram 
MgS04 . 7 H 2 O . 0.5gram 
NaCl.... 0.1 gram 
FeS04_0.02 gram 
Distilled water__1,000 c. c. 
One per cent of the various proteins 
and amino acids was added to the 
above medium. Pure or anhydrous 
dextrose was used in 2 or 1 per cent 
concentrations. The amino acids were 
purified commercial products and con¬ 
sisted, therefore, of the racemized 
forms. The casein was purified accord¬ 
ing to Hammarsten and brought into 
solution, by dissolving 1 gm. of casein 
in 8 c. c. of 0.1N NaOH then adjust¬ 
ing the reaction with HC1. The media 
were placed, in 100 c. c. portions, in 
250 c. c. Erlenmeyer flasks, plugged 
with cotton and sterilized at 10 pounds 
for 30 minutes. The media were then 
inoculated with the various organisms 
grown on agar slants. 
The following organisms have been 
used in this study: 
Trichoderma koningi Oud. and 'Zygor- 
hynchus molleri Vuill. isolated from the 
soil and kept in culture for some time . 
Adinomyces viridochromogenus (Kra- 
insky) Waksman isolated from the 
soil in 1916 and described in detail else¬ 
where. 
Bacillus cereus Frankland isolated 
from the soil. 
Bacterium fluorescens (Fltigge) Lehm. 
et Neum. isolated from the soil. 
The following procedure of analysis 
was used. At the end of the period of 
incubation the cultures were filtered 
through weighed pieces of ashless filter 
paper and the mycelium washed with a 
little distilled water so as to bring the 
filtrate to original volume. The myce¬ 
lium was then dried to constant weight 
at 65° to 85° C., then analyzed for 
