ANTIBACTERIAL EFFECTS 137 



usually high yields of penicillin in submerged culture (475). On ex- 

 amination in plate culture as well as microscopically, these high-peni- 

 cillin-yielding mutants resembled the parent strains from which they 

 were isolated. Some of the high-yielding cultures are relatively stable j 

 others, however, are quite unstable, giving substrains with substan- 

 tially greater yields of penicillin. Light-sporing substrains give reduced 

 yields J white nonsporulating strains are characterized by low yields 

 (764). Some of the most productive strains were found to vary pri- 

 marily in biochemical activity, and only little in cultural or structural 

 details. Some of the variations are brought out in Tables 25 and 16 and 

 in Figures 14 and 15. 



TABLE 25. PRODUCTION OF PENICILLIN IN SUBMERGED CULTURE BY 

 NRRL 832 AND THREE SELECTED SUBSTRAINS 



From Raper and Alexander (764). 



TABLE 26. PRODUCTION OF PENICILLIN IN SURFACE CULTURE BY NRRL 

 I249.B2I, 1950, 1978, AND TWO SUBSTRAINS OF 1 978, A AND B 



From Raper and Alexander (764). 



