METHODS OF GROWING ANTAGONISTIC ORGANISMS 67 



Phenylacetic acid and its derivatives have a marked effect upon peni- 

 cillin yields 5 frequently amide derivatives are just as effective as the 

 corresponding acids (887). 



With the introduction of the submerged process for the production 

 of penicillin, it became necessary to find a simple means of obtaining 

 large numbers of spores. For this purpose, a medium high in calcium 

 salt appears to be essential (282). Such a medium is as follows: 



Sucrose or brown sugar 20.0 gm. 



NaNOo 6.0 gm. 



KH2PO4 1.6 gm. 



MgS04.7HoO 0.5 gm. 



CaClo 25.0 gm. 



Tap or distilled water to make lOOO ml. 



The culture is grown for 4 to 6 days with continuous aeration and agi- 

 tation. 



Various other methods are used for spore production, for the purpose 

 of inoculating large batches of medium. For surface growth, dry spores 

 are mixed with a floating and spreading agent, such as whole wheat 

 flour. 



Other media, such as bran (762), have been utilized to a limited 

 extent for the production of penicillin. However, the submerged proc- 

 ess, accompanied by agitation and aeration, using one of the above 

 liquid media has now come into general use for large-scale production 

 of penicillin. 



