296 



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



[VOL. 60 



types of B. abortus to the toxicity of alanine a series of flasks of G-W medium 

 (100 ml) were inoculated with smooth or rough organisms. To each culture 

 was added sufficient DL-alanine to yield final concentrations of 100 ng, 200 ng, 



4x10* 



I x t0° 



IxlO' 



3xl0 6 



I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 



DAYS 

 Figure 4- Growth (viable cell counts) of rough B. abortus in the presence of different con- 

 centrations of DL-alanine. 



TABLE 3 



Growth and variation of smooth B. abortus in synthetic medium containing different 

 concentrations of DL-alanine 



* Averages of 6 plates. 



t Predominantly rough type. 



500 Mg, or 1,000 Mg per ml of medium. Upon repeated sampling of these cultures 

 during incubation it was found that alanine in a concentration of 100 ng per 

 ml or more exhibited a significant growth-depressing effect on the smooth type, 

 whereas the rough variant was unaffected until a concentration of 1,000 Mg of 



138 



