METABOLISM OF ACTINOMYCETES 17 



Of the different amino acids used, leucin tends to result in a 

 more acid medium, while asparagin and glycocoll lead to a 

 neutral or slightly alkaline reaction. The leucin medium changed 

 on the average for the organisms studied for the first period from 

 pH 7.3 to pH 6.7 and 6.43, while the glycocoll media changed 

 on the average from 7.1 to 7.23 and 7.33, allowing for the varia- 

 tion of the organisms. The protein and peptone media all 

 tended to become more acid, but not to such as extent as the 

 leucin media. It is possible that the reaction of media contain- 

 ing certain proteins may change either to acid or alkaline de- 

 pending entirely upon whether the organism attacks one amino 

 acid group or another in the protein molecule. The final hydro- 

 gen-ion concentration of media, upon which miroorganisms have 

 grown in the presence of the same carbohydrate, is influenced by 

 the nitrogen source and varies greatly, depending upon the 

 source of nitrogen. A more detailed study of this question will 

 be found in the following paper of this series. 



The utilization of tyrosin and creatinine by actinomycetes 

 was also studied; the results for the first are reported below in 

 table 3, while creatinine was readily used as a source of nitrogen 

 by all species tested, accompanied by a slightly acid reaction 

 (pH usually changing from 7.0 to 6.4-6.8); the growth was 

 always fair to good and consisted of colonies throughout the 

 medium or as flakes on bottom of tube. No. 205 produced a 

 characteristic soluble yellow pigment, A. viridochromogenus, and 

 A. pheochromogenus a brownish and A. violaceus-ruber a bluish pig- 

 ment, while A. scabies, A. aureus and A. exfoliatus produced no 

 pigment at all. 



A word should be said concerning the pigment production by 

 the actinomycetes upon the media containing proteins and 

 amino acids. These pigments are very characteristic of the 

 species and seem to be stimulated by the organic nitrogen. 

 The chromogenus species, reported in table 1 include A. scabies, 

 A. viridochromogenus, A. aureus and to some extent A. bobili, 

 A. ruber and A. reticuli. These species are characterized by a 

 brown or dark brown (yellowish in few cases, particularly accom- 

 panying poor growth) pigment which slowly dissolves into the 

 medium. 



THE JOURNAL OF BACTERIOLOGY, VOL. V, NO. 1 



