44 



SELMAN A. WAKSMAN AND JACOB S. JOFFE 



the glucose medium to a slight acid, but the increase in acidity 

 was a good deal less than that produced by the bacteria or 

 even by Aspergillus niger. It may be quite possible that 

 some actinomyces produce certain acids from carbohydrates, 

 but to explain the change in reaction produced by these organ- 

 isms in the medium, we must look rather towards their action 

 upon the proteins. The carbohydrates affect the change in 

 reaction by affecting the protein metabolism of the actinomycetes. 

 Gillespie (1918), has pointed out that A. scabies will not develop 

 in a medium that has a lower exponent than pH — 4.8 to 5.2. 



TABLE 5 



The effect of glucose upon the change in reaction produced by microorganisms in the 



medium 



ORGANISM 



Control 



B. coli 



B. proteus 



Aspergillus niger 



A. diastaticus 



A. viridochromogenus 



A . f radii 



A. griseus 



A. poolensis 



A. scabies 



NO GLUCOSE 



Three days Seven days 



pH 



8.2 

 7.5 



8.1 

 8.4 

 8.4 

 8.6 



8.6 



7.8 



pH 



8.2 



9.0 

 8.3 



8.8 

 8.3 

 8.5 



7.8 



7.7 



1 PER CENT GLUCOSE 



Three days Seven days 



pH 



7.8 

 6.0 

 6.6 

 7.4 

 7.6 

 7.8 



7.7 



7.6 



pH 



7.8 

 4.8 

 5.2 

 7.1 

 7.5 

 7.3 

 7.5 

 7.7 

 7.2 

 7.3 



The effect of reaction upon the growth of actinomycetes was 

 studied by us both in synthetic and organic media. 



A series of synthetic media were made up having different 

 hydrogen-ion concentrations adjusted by the use of buffers. 

 Each medium contained 30 grams glycerol, 0.5 gram MgS0 4 , 

 0.5 gram KC1, 0.01 gram FeS0 4 and 5 grams asparagin per 

 liter. The reaction was adjusted by the use of phosphates and 

 carbonates. 



The cultures were inoculated in duplicate, as usual, from the 

 same mother culture, and incubated at 25°. At the end of 

 fifteen days, the cultures were examined and pH values of solu- 

 tions determined. 



