PROTEIN SYNTHESIS BY A20T0BACTER' 
By O. W, Huntkr 
Associate Bacteriologist^ Kansas Agricultural Experiment Station 
The metabolic process of protein synthesis is common to all micro¬ 
organisms. The rate, form, and total quantity of protein synthesized, 
however, as well as the type of food substances available for synthesis, 
varies widely. 
An idea of the relative protein content of microorganisms can be 
obtained from the results recorded by various investigators; but the 
multiplicity of the methods employed in the cultivation, collection, and 
analysis of microbial cells makes a comparative study difficult. A high 
nitrogen content for most bacteria is reported. If all of this nitrogen be 
considered as protein nitrogen, the protein content of such cells is large. 
Wheeler {8, p. 65),* whose results seem to be comparative for such 
analyses, reports a nitrogen content varying from 5.964 per cent to 
11-765 per cent for 12 bacteria examined. The nitrogen content of 
yeasts is probably similar to that of bacteria. Nicolle and Alilaire (5) 
report a nitrogen content of lo.o per cent for a Froberg yeast. 
The high protein content of yeasts, their rapidity of ^owth, and their 
practical method of cultivation justify their wide exploitation as a food 
product within recent years. The value of such yeast food as a 
protein concentrate appears to be firmly established. During the recent 
war the demand for tibiis yeast concentrate in Germany far exceeded the 
supply. 
Interest in the yeast industry has been accentuated with the develop¬ 
ment of the present vitamine theory. The high content of water-soluble 
B vitamine in yeast cells has apparently opened a new field for its use. 
Several factors tend to influence the practicability of utilizing micro¬ 
organisms as a source of protein. Mechanically, the problem is dependent 
upon the development of practical methods for securing a maximum 
degree of growth, as well as means for the collection and care of the 
product. Economically, the yield, rate of growth, and the food require¬ 
ments of the organism are important considerations. The substances 
used as food for the organism should be in the nature of waste products, 
and to justify the process the s^ynthesized product must have a greater 
value than the substances used in its production. Finally, if the industry 
is to be of value, the product must have a nutritional value. 
The high protein content of the Azotobacter cell and its relatively 
simple food requirements suggested the possibility of utilizing it as a 
means for synthesizing a protein which could be used either as a stock 
food or as a fertilizer. The employment of this organism for such a 
purpose appeared to offer some important advantages on account of its 
nitrogen-assimilating ability. This would necessitate the use of a solu¬ 
tion having a carbohydrate only as the important constituent. 
On the other hand, the apparent slow development of Azotobacter 
seemed to present a serious difficulty. However, it has been demonstrated 
> Accepted for publication May 31, 192a. 
Contribution No. 40 from the Bacteriological laboratories of the Kansas Agricultural Experiment 
Station. 
* Reference is made by number (italic) to literature cited,” p. 274. 
(263) 
Journal of Agricultural Research, 
Washington, D. C. 
abi 
Vol. XXIV, No. 3 
Apr. 21, 1923 
Key No. Kans.-33 
