12 
North Carolina Agricultural Experiment Station 
production of acidity as occurs during sterilization. Since these strains form 
acid weakly, their reactions are not evident with media whose initial reac¬ 
tion, as determined by titration with phenolphthalein is approximately pH= 
8.5. When, however, the initial reaction closely approximates absolute neu¬ 
trality, as determined colorimetrically, small increases in acidity consequent 
on growth are detectable. This is shown particularly in the case of No. 19, 
which with litmus agar adjusted to pH=8.0-8.5 gives no evidence of its ability 
to form acid with saccharose. A similar condition has been reported by Jones 
(4) for a strain of Pneumococcus which when inoculated into a medium whose 
initial reaction was pH 7.0 grew poorly and developed a final concentration of 
only pH 6.2, whereas in a medium whose initial reaction was pH 7.6 growth 
was abundant and a concentration of pH 5.4 was developed. 
It has been possible to verify previously published accounts of the morphol¬ 
ogy and cultural characters of the soybean bacterial blight organisms in all 
respects except in the reaction toward the several sugars. Nos. 268 and 269, 
which in Miss Coerper’s discussion on variations of strains (1 1. c. p. 189) are 
called Strain A, are regarded as identical and are the type of Bacterium gly- 
cineum. They have the same reaction toward dextrose, saccharose, lactose, 
maltose, and glycerine, from the first two of which they form acid rather 
strongly, but from the others, in small amounts and slowly. They furthermore, 
consistently cause a browning of the media. Nos. 211 and 270, which are 
called Strain E, are like No. 19, the type of B. sojae. They are able to form 
acid from dextrose and saccharose alone and agree in being non-pigment 
forming.* 
SUMMARY 
A comparison has been made of bacterial blight of soybean as described 
from Wisconsin and from North Carolina. The diseases differ somewhat in 
appearance, but these differences are of minor importance and it is doubtful 
if one could differentiate them with certainty in the field. By the use of 
certain easily operable refinements which consist essentially in adjustment 
of initial reaction to neutrality and in reducing the hydrolyzation of sugars to 
negligible quantities, it is determined that the several strains of bacteria patho¬ 
genic to soybeans represent two distinct species, Bacterium glycineum and B. 
sojae. They differ principally in that the former produces brown pigment 
with certain media and forms acid from dextrose, saccharose, lactose, mal¬ 
tose and glycerine, whereas the latter is non-pigment forming and forms acid 
from the first two of these sugars only. Both organisms have been isolated 
in Wisconsin and proven to be pathogenic, and B. sojae alone has been found 
to be associated with soybean blight in North Carolina. 
*In fermentation studies conducted during the summer of 1921, additional 
evidence was secured of differences of specific rank between Nos. 19 and 268. 
In bouillon consisting of 1 per cent peptone, 0.3 per cent beef extract, 0.5 per 
cent NaCl, and 1 per cent of either mannite, galactose, or dextrine, Bacterium 
glycineum was able to ferment both mannite and galactose, but not dextrine, 
with the formation of acid. No acid was formed from any of these carbohy¬ 
drates by B. sojae. The initial reaction was adjusted to pH 7.2 in all cultures. 
By the seventh day, with B glycineum, the reaction with mannite had changed 
to pH 6.4, with galactose, pH 5.2 and with dextrine pH 7.8. In the case of B. 
sojae, 7.6, 7.8 and 7.8 represented the corresponding H ion concentrations re¬ 
spectively on the seventh day. F. A. W. 
