The Effect of Medium Constituents

Since the discovery of the stimulating effect of corn steep liquor on penicillin fermentation, various lactosesteep liquor media have been used in penicillin fermentations. The requirements for a good penicillin fermentation are fulfilled by the steep liquor-lactose media by virtue of its composition (Johnson, 1952). The production of penicillin on a chemically defined medium (Jarvis and Johnson, 1947) is evidence for the absence of any unknown essential factors in steep liquor. Therefore, natural materials other than steep liquor should be suitable for media for penicillin production, provided that the constituents of such media are properly balanced. Several attempts have been made to replace steep liquor with various organic nutrients in surface culture medium. Cook and Tulloch (1944) advocated the use of pressed juice from fresh peas as a substitute for steep liquor. Wheat bran moistened with an equal weight of water was proposed by Rao (1944). Foster et al. (1946) reported that cottonseed meal had potentialities as a possible substitute for steep liquor in submerged penicillin fermentation. Perlman (1949) also showved that several protein materials may be used as substitutes for steep liquor without marked reduction in penicillin yield. In the work reported here, a number of organic materials were used as nitrogenous nutrients in penicillin production. In each case, an attempt was made to adjust the concentrations of the constituents of the medium so that the best environmental requirements for penicillin production would be obtained. Changes made in the composition of the medium were on the basis of information obtained from analyses made during the fermentations. These studies have shown that with proper adjustment of the composition of the medium a wide variety of materials may be used as carbon and nitrogen sources in the penicillin fermentation.