1923] 



JENNISON — POTATO BLACKLEG 45 



III. Carbohydrate Utilization by Strains of the Blackleg 



Bacillus and Other Microorganisms 



In spite of the fact that the strains of the blackleg bacillus 

 employed by the writer in earlier studies showed no signs of 

 diastatic action on potato starch jelly, it was nevertheless some- 

 what difficult to conceive of a virulent parasite of the potato 

 totally lacking the power of hydrolyzing starch. This thought, 

 together with a rather extensive knowledge of the gas- and acid- 

 producing capacity of this bacillus, suggested the desirability of 

 investigating these relations in a quantitative manner. The 

 writer had employed Shaffer's ('14) modification of the volumet- 

 ric method of Bertrand for the quantitative estimation of re- 

 ducing sugars in the presence of proteins and albumins. Famil- 

 iarity with this method led me to conclude that with its aid 

 reliable data could be obtained concerning the quantitative con- 

 sumption of certain sugars and starch by the blackleg bacillus 

 as well as by other microorganisms with which it appeared. 

 Very little, if anything, had been published upon the quantita- 

 tive consumption of carbohydrates. Accordingly, plans were 

 made to investigate quantitatively these relations in certain of 

 the strains of the potato blackleg bacillus as well as in other 

 species of bacteria. Some points of interest in this connection 

 have, however, recently been contributed by Besson, Ranque, 

 and Senez ('19). Working with Bacillus coli in nutrient broth 

 containing varying amounts of dextrose, they found that when 

 less than 0.4 per cent dextrose was furnished all the sugar was 

 removed in 24 hours. 





materials and methods 



After numerous experiments a method was developed whereby 

 reliable data were obtained. The work of Shaffer and Hartmann 

 ('21) on the iodometric determination of copper and its use in 

 sugar analysis had not appeared at the time the writer per- 

 formed the experiments reported herewith. Undoubtedly, the 

 newer methods would have greatly facilitated prosecution of 

 this phase of the work, but it is doubtful if more accurate results 

 could have been obtained. 



Certain strains of the blackleg bacillus used in the preceding 

 studies were selected for investigation and comparison in this 

 connection, i. e., Nos. 160.1, 180.2, 183.2, 187B.1, 195, 197, 198, 

 201. Pure cultures of the following were also tested : Bacillus coli 



