The Effect of Certain Chemicals on Penicillin Production and Mold Metabolism in Shake Flask Fermentations

Abstract

Of 49 chemical compounds and mixtures tested for their ability to raise penicillin levels in shake flask cultures, only citric acid and borax or boric acid proved to be stimulatory. The degree of stimulation varied with strains. Citric acid showed an opt. stimulatory action at a conc. of 0.0005 [image] with Penicillium notatum strain NRRL 832, but not with Penicillium R-38 and P. chrysogenum NRRL 1951-B25. Borax and boric acid were most stimulatory at a level of 0.2% and 0.13%, respectively, with strain NRRL 1951-B25, but not with strain NRRL 832. The stimulatory effect of borax and boric acid was indicated as due to the boron and was not attributable to a pH effect or to impurities of the reagents. There was a general tendency for borax and for compounds with doubtful stimulatory power to stimulate runs with low-yielding but not with high-yielding control fermentations. A list of chemicals that might stimulate penicillin production, but whose action was irregular, is given; compounds lacking in stimulatory power or possessing depressing powers were also enumerated. The effect of boric acid on the metabolism of P. chrysogenum NRRL 1951-B25 was studied. The B-fed mold differed from the control in these aspects: it utilized lactose more rapidly, had a higher rate of respiration and N utilization, had a less abundant mycelium which contained less N, and had an internal balance which was reflected outside the organism in lower ammonia levels and higher penicillin yields[long dash]Stimulatory substances might be of importance commercially; how these compounds could be used as tools in the study of the mechanism of penicillin production, is indicated.