PRODUCTION OF A GROWTH-PROMOTING SUBSTANCE 
BY AZOTOBACTER 1 
By O. W. Hunter 
Associate Bacteriologist , Kansas Agricultural Experiment Station 
It is maintained by many investigators that the animal cell is incapable 
of synthesizing vitamines and that such cells are thus required to obtain 
their food accessories from the vegetable kingdom. If this is true, it can 
logically be asked, do plants need such growth promoting factors? If 
so, do they synthesize them or from what source are they obtained ? 
Bottomley’s (2) 2 experiments on peat led him to state that the growth 
of plants require food accessories or auximones. He grew aerobic soil 
organisms in peat for several days. This was then sterilized, inoculated 
with Azotobacter and incubated. As a result there were produced in the 
peat substances which greatly stimulated plant growth. Similar results 
were obtained by Mockenridge (4) and Jones (j). 
The application of the vitamine theory to microbial nutrition is now 
prevalent. While there has been a large amount of attention focused 
upon the need of food accessory factors for the normal growth of micro¬ 
organisms, but little thought has been placed upon the vitamine content 
of microorganisms or their ability to synthesize such, regardless of the 
fact that one of the most abundant known supplies of the so-called 
w r ater-soluble B vitamine is found in a one-celled organism, the yeast. 
This vitamine content of yeast was first reported by Funk (/). 
Pacini and Russell (5), from their experiments concluded that Bacillus 
typhosus Eberth-Gaffky can manufacture vitamines and can likewise 
stimulate growth of the animal cell. They grew B . typhosus in a syn¬ 
thetic medium, the bacterial cells from which were collected and ex¬ 
tracted with alcohol. The alcoholic extract was evaporated down to 
dryness and the residue dissolved in water. This extract was used in 
their feeding experiments on white rats. 
Recently much attention has been directed toward the use of yeast for 
the quantitative measurement of the vitamine content of test substances, 
the principle of which is dependent upon the assumption that the yeast 
needs a food accessory factor for its growth in an inorganic synthetic 
medium. This accessory factor is considered identical with the water- 
soluble B vitamine. 
Experiments to determine the reliability of the test appear to have 
brought forth some interesting facts. This dependence of yeasts upon 
the antineuritic vitamine is doubted by MacDonald and McCullom (7). 
1 Accepted for publication Jan. 16, 1922. Contribution No. 39 from the bacteriological laboratories of the 
Kansas Agricultural Experiment Station, reporting in part the results of project No. 138. 
2 Reference is made by number (italic) to “ Literature cited,” p. 831. 
Journal of Agricultural Research, 
Washington, D. C. 
act 
( g2 5) 
Vol. XXIII, No. 10 
Mar. 10, 1923 
Key No. Kans.~3i 
