Dec. io. 1913 
Disease of Sugar-Beet and Nasturtium Leaves 
209 
COMPARISON OF BACTERIUM XANTHOCHEORUM WITH BACTERIUM 
APTATUM 
While investigations with Bacterium aptatum were in progress, atten¬ 
tion was called to the recent work of Dr. Julius Schuster upon a bacterial 
decay of the potato tuber caused by Bacterium xanthocktorum} From 
Dr. Schuster's description it was observed that in morphological and 
certain cultural characters this potato bacterium resembled quite closely 
Bacterium aptatum. Since both belong to the green fluorescent group 
of bacteria, it seemed worth while to take up a comparative study of 
the two organisms. Fortunately a culture of Dr. Schuster's Bacterium 
xanthocktorum was at hand, having been brought to our laboratory by 
Dr. H. W. Wollenweber in November, 1911. Accordingly a series of 
cultural tests was begun at once and continued for a period of about 
three months. 1 2 As a result of these tests it is evident that Bacterium 
aptatum and Bacterium xanthocktorum are not identical, although their 
appearance is quite similar upon some kinds of culture media. Table 
IV gives a partial record of the results obtained and will be sufficient 
to show the differences. 
Table IV. —Comparison of the cultural characteristics of Bacterium aptatum and 
Bacterium xanthochlorum . 
Media. 
Bacterium aptatum. 
Bacterium xanthochlorum. 
+ 15 beef-agar plates. 
+15 beef-agar stroke. 
+ 15 beef-agar stab. 
-f 10 gelatin plates. 
-f is beef bouillon. 
Potato cylinders. 
Nitrate bouillon. 
Sterile milk. 
Litmus milk.. 
Uschinsky’s solution.... 
Litmus-lactose agar. 
Growth less rapid than Bacterium 
xanthochlorum; fishscalelike mark¬ 
ings on surface colonies pronounced. 
Growth less rapid than Bacterium 
xanthochlorum and greenish fluor¬ 
escence not so marked. 
Growth whitish to drab color in center 
of nail head. 
Growth slower than Bacterium xan¬ 
thochlorum and liquefaction does 
not begin so early; medium only 
slightly greened. 
Thin pellicle of pseudozoogloeselike 
masses; sediment a ropelike viscid 
swirl; fluorescense appears slowly. 
Appearance similar to Bacterium xan¬ 
thochlorum. 
Less rapid growth than Bacterium 
xanthochlorum; pellicle easily break¬ 
ing into small particles; fluorescence 
weak. 
Slow separation of whey from curd; 
no distinct fluorescence; pellicle of 
floating islands. 
Color of whey blue with whitish rim 
formed around tube above solution; 
pellicle not complete. 
Clouding less dense than Bacterium 
xanthochlorum; fluorescence mod¬ 
erate; pellicle composed of pseudo- 
zoogloeae-like masses. 
Growth less rapid than Bacterium 
xanthochlorum; blue in color; me¬ 
dium blued; precipitate lead colored. 
Growth more rapid and appearance of 
colonies more compact than those of 
Bacterium aptatum. 
Growth rapid and fluorescence marked. 
Growth pinkish colored in center of 
nail head. 
Growth and liquefaction rapid; me¬ 
dium distinctly greened. 
Growth rapid; pellicle membranous 
and falling entire; green fluorescence 
striking. 
Growth gradual; at first creamy white, 
later brownish; starch not broken 
down. 
Growth rapid; pellicle membranous 
and breaking into fragments; fluor¬ 
escence much greater than Bacterium 
aptatum. 
Separation of whey from curd more 
rapid than in Bacterium aptatum; 
pellicle more distinct; greenish fluo¬ 
rescence marked. 
Color of whey grayish; rim above solu¬ 
tion pink to purplish; pellicle dis¬ 
tinct. 
Clouding dense; pure green fluores¬ 
cence; membranous pellicle. 
Growth rapid and dense; color of 
growth, greenish blue; medium 
blued; precipitate brownish. 
1 Schuster, Julius. Zur Kenntnis der Bakterienfaule der KartofTel. Arb. K. Biol. Anst. Land- u. 
Forstw., Bd. 8, Heft 4, p. 452-492, 13 fig., pi. 5, 1912. 
2 The bacterium isolated from nasturtium leaves was used in these tests. 
