40 Biochemical Activity of Micro organisms [March, 



and cooked for a half hour in an autoclave. The cooking process 

 breaks the coagulated albumen into small particles and gives a 

 cloudy medium. This agar is then poured into Petri dishes and, 

 when soHd, inoculated with the desired organisms. As the colonies 

 develop they digest the coaguhim and a halo of clear agar surrounds 

 the colony (Plate i, Fig. 5). The results of tests of the tryptic 

 activity of certain organisms on egg-albumen-agar are given in 

 Table 9. 



Amidase. Amidase is an enzyme capable of attacking amino 

 Compounds and forming ammonia along with other cleavage prod- 

 ucts. Upon this liberation of ammonia is based the following test. 



Asparagin-rosolic-acid-agar. To the stock agar is added 0.5 

 percent of asparagin and 5 c.c. of 2 percent rosolic acid per liter. 

 The rosolic acid, which is yellow with acid, gives this medium a 

 slight yellow tint. The liberation of ammonia from the asparagin 

 renders the medium alkaline, and the rosolic acid takes on a brilliant 

 red color. This is a beautiful reaction and a highly satisfactory 

 test for the production of amidase by lower organisms. See 

 Table 10. 



TABLE 10 



Data pertaining to tcsts for amidase-production on asparagin-rosolic-acid-agar 



Organism Growth Reaction 



B. fluoresccns liquifaciens . . . Good Deep brilliant red, diffusing 



B. putidum Very good Deep red 



B. ccrogenes Good Red, little diffused 



B. prodigiosus Fair Slight red, little diffused 



Bact. lactis acidi Very good Deep red, widely diffused 



B. denitrificans Very good Deep red, widely diffused 



Bact. tumefaciens Very good Deep red, widely diffused 



B. pyocyaneus Very good Deep red, widely diffused 



B. coli Very good Deep red, widely diffused 



Actinomyces bovis Very good Deep red, widely diffused 



B. hartlebii None 



B. butyricus Slight or none No change 



B. megatherium Slight No change 



B. radiatum Slight No change 



B. campestris Slight No change 



B. amylovorus Slight No change 



B. vulgaris Slight No change 



B. subtilis Slight No change 



B. mvcoidcs Slight No change 



M. citricus Slight No change 



Sarcina alba Slight No change 



Sarcina lutea Slight No change 



Oospora Scabies None No change 



Streptothrix sp None No change 



Pseudopeziza ribis Good Slight red 



Glonicrella rufoniaculans Very poor No change 



Hehninthosporium turcicum . . Poor Very deep red, not diffused 



