Apr. 91,1993 
Protein Synthesis by Azotobacter 
273 
The data show a net gain of nitrogen in favor of the straw medium 
for all cultures. The average net gain of nitrogen for all cultures grown 
in the molasses solution was 2.38 mgm. and for those grown in the straw 
solution 5.10 mgm. This gives an average of net balance in favor of 
the straw media of 2.72 mgm. 
Another experiment was conducted in which two flasks containing 
200 cc. of straw-molasses solution were seeded with two Azotobacter 
cultures and aerated for three days. Ferric-sulphate solution was added 
to precipitate the protein in each culture flask. The entire contents of 
ea(ii flask were then placed upon a filter, and the residue was collected. 
This precipitate was desiccated and total nitrogen determinations were 
made. A control medium was treated in a similar manner. The results 
are presented in Table IX. 
TablK IX .—Effect of straw arid molasses on azofication 
Culture No. 
Total nitrogen 
per gram of 
straw. 
Net nitrogen 
per gram of 
straw. 
Control.. 
Mgm, 
II. 18 
IC. 2LI 
Mgm, 
2^2 ... 
J.. 22 
X B. 
15.84 
4.66 
The experiment shows an average net gain of 4.44 mgm. of nitrogen 
per gram of straw, or 2.77 per cent protein. 
SUMMARY 
(1) The protein content of Azotobacter growth obtained from a solid 
medium was found to be 11.81 per cent, while that collected from a 
liquid culture was 30.56 per cent. 
(2) The 3rield of cells increased with the quantity of dextrose in the 
medium. An average yield of 15.7 per cent, 20.2 per cent, and 25.9 
per cent of the sugar was obtained from medium containing 0.6 per cent, 
1.1 per cent, and 1.5 per cent dextrose, respectively. 
(3) The relative quantities of nitrogen fixed per gram of dextrose for 
the three different percentages of sugar were similar—^namely, 16.1 
mgm., 17.0 mgm., and 17.3 mgm., respectively. 
(4) When molasses was used as a source of energy for Azotobacter 
development there was obtained a yield of cells equal to 30.44 per cent 
of the sugar in the molasses. This gives a higher percentage yield for 
the molasses sugar than for dextrose. If the moisture content of the 
molasses is considered, the percentage yield from the actual molasses 
•exceeds the yield from dextrose. 
(5) Azotobacter is able to convert the soluble nitrogenous substances 
present in molasses into more complex protein, as well as to utilize the 
molasses as a source of energy for the Nation of atmospheric nitrogen. 
(6) The addition of straw to the dextrose or molasses medium did 
not cause any appreciable increase in the quantity of nitrogen fixed. 
