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R. J. GOODLOW, L. A. MIKA, AND W. BRAUN 



[VOL. 60 



growth and variation of smooth cultures. The increase of the viable smooth 

 organisms was repressed, and an earlier and more rapid establishment of non- 

 smooth variants occurred (table 2). When such filtrates were added to freshly- 

 inoculated rough B. abortus cultures, only a slight inhibitory effect on the growth 

 of the rough organisms was observed. Subsequent experiments demonstrated 

 that the smooth-suppressing factor in filtrates was dialyzable and heat-resistant 

 (100 C for 5 minutes). 



Paper chromatograms were then prepared daily on filtrates of actively grow- 

 ing smooth cultures in G-W medium. Until the eighth or tenth day of growth 

 these chromatograms showed no spots, other than those of asparagine and aspar- 



TABLE 2 



Growth and variation of smooth B. abortus in synthetic medium after addition of old culture 



filtrate 



* Averages of 6 plates. 



t Predominantly rough type. 



tic acid. After that period another spot with the Rf value of glutamine, thre- 

 onine, or alanine made its appearance. The use of collidine-lutidine 2 solvent 

 subsequently indicated that this spot was probably due to alanine. Further obser- 

 vations showed that this spot became more intense during the subsequent 10 

 days of growth. After this time no further differences in intensity were visible. 

 Because of the interesting correlation between the appearance in the culture 

 medium of this amino acid and the simultaneous increase in the establishment 

 of nonsmooth variants, the effects of adding glutamine, threonine, or alanine to 

 freshly inoculated smooth cultures were tested. Neither the addition of 0.5 mg 

 per ml glutamine nor 0.015 mg per ml of DL-threonine resulted in any appreci- 

 able change in growth and variation when compared with control cultures. The 

 addition of 0.5 mg per ml DL-alanine resulted, however, in a marked suppression 



2 Thirty -five per cent collidine (mixed), 35 per cent 2,6-lutidine, and 30 per cent distilled 

 water. 



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