Penicillin production by high-yielding strains of Penicillium chrysogenum.

The development and study of strains of Penicillium chrysogenum that give high yields of penicillin has been a major project at the University of Wisconsin during the past 12 years. Many thousands of cultures have been screened for their penicillin-producing ability in the Botany Department of the University. The methods used for the production and screening of mutants, the genealogy of the outstanding strains and their cultural characteristics have been described recently by Backus and Stauffer (1955). In recent years, interest has centered on cultures that produce no pigment but give high yields of penicillin. Many of the superior cultures have been studied intensively both in shaken flasks and pilot plant fermentations in the Biochemistry Department (Anderson et al., 1953, 1956; Davey and Johnson, 1953; Soltero and Johnson, 1954; and Owen and Johnson, 1955). In the present paper we shall report on factors affecting penicillin production by some of the recent high-yielding strains. These are numbered W50-935, W50-1583, W51-20, W51-616, W51-20F3, and W51-20F3-64.