Apr. 31, 1923 
Protein Synthesis by Azotobacter 
271 
this nitrogen had been synthesized into a more complex nitrogenous 
substance by the growth of Azotobacter. 
Eight flasks containing 250 cc. of molasses medium were inoculated, 
four with cultiure No. 19 and four with culture No. 232, and aerated 
thoroughly for eight days. 
The contents of the four flasks of each culture were mixed, and total 
nitrogen determinations were made. The remaining portion was pre¬ 
cipitated with a lead-acetate solution and filtered. This filtrate was 
perfectly clear. Total nitrogen determinations were likewise made on 
this filtrate. The control medium was treated in a similar manner. 
The average results for all duplicate determinations are as follows: 
Control. 
Azotobacter No. 19. 
Azotobacter No. 232 
fMedium 6.71 mgm. nitrogen per 100 cc. 
iFiltrate, 6.40 mgm. nitrogen per 100 cc. 
fCulture 9.52 mgm. nitrogen per 100 cc. 
\Filtrate 0.8 mgm. nitrogen per 100 cc. 
fCulture 10.30 mgm. nitrogen per 100 cc. 
iFiltrate o mgm. nitrogen per 100 cc. 
From these results it is evident that Azotobacter is capable of synthe 
sizing the nitrogen present in the molasses into more complex substances 
as well as assimilating nitrogen from the air. 
UTILIZATION OF STRAW 
Pringsheim and Lichtenstein (15) report an investigation the purpose 
of whidi was to enrich straw concentrate with protein by means of fungi. 
Hydrolyzed straw was spread out in thin layers and inoculated with an 
Aspergillus. The protein content of the straw increased from 0.9 per 
cent to 8.0 per cent within a week Digestion experiments with the food 
proved satisfactory. 
The utilization of vegetable tissues as available sources of energy for 
Azotobacter has been Reported by Murray (j j) and Hutchinson { 12 ) , 
Experiments were undertaken in the present case with a view to 
increasing the protein content of wheat straw by Azotobacter. To each 
200 cc. of a dextrose, and also a molasses medium, there was added i 
per cent of a good grade of wheat straw which had been finely ground 
in a mill. This was seeded with Azotobacter cultures and aerated for 
varying lengths of time. Total nitrogen determinations were made in 
duplicate on the entire contents of the culture flasks. To note the effect 
of straw in the medium, similar determinations were made on cultures 
containing no straw. 
The results are recorded in Table VI for three cultures aerated in the 
dextrose solution and in the straw dextrose medium for four days. 
Tabl^ VI .—Effect of straw on azofication 
Culture No. 
Dextrose-Ashby medium 
(200 cc.). 
Dextrose-Ashby and straw 
medium (200 cc.). 
Nitrogen 
in 
control. 
Total 
gross 
nitrogen. 
Net 
nitrogen. 
Nitrogen 
in 
control. 
Total 
gross 
nitrogen. 
Net 
nitrogen. 
Mgm. 
Mgm. 
Mgm. 
Mgm. 
Mgm. 
Mgm. 
1 B. 
1.4 
7. 80 
6.4 
9.4 
20. 01 
106. I 
10 B. 
1.4 
8. 08 
6. 68 
9.4 
19. 86 
10. 46 
232 . 
1.4 
9.97 
8. 57 
9.4 
22. 36 
12. 96 
