Cultural Characteristics of Penicillium Notatum in Relation to the Production of Antibacterial Substance: Indication of the Dual Nature of the Antibacterial Substance.

Of the bacterial antagonists thus far known to be produced by microorganisms, the most effective in bactericidal action against Brucella abortus is the culture filtrate from a strain of Penicillium notatum (Kocholaty, 1942). Another antibacterial substance, penicillin, also obtained from a culture of a strain of Penicillium notatum, but with very little potency against Brucella abortus, has been obtained and purified by a group of British workers (Abraham, Chain, Fletcher, Florey, Gardner, Heatley, and Jennings, 1941). The work reported here deals chiefly with the cultural habits of a certain strain of Penicillium notatum with special regard to the production of an antibacterial substance against Brucella abortus. Distinction is drawn between penicillin and the antibacterial substance active against Brucella abortus, because the evidence thus far indicates that those two are not identical. As compared to previous results, it has been possible to increase the production of the antibacterial substance of the mold by about 10 times, so that 0.01 ml. of the crude culture filtrate, added to 10 ml. of tryptose agar will either strongly inhibit or completely suppress the growth of BruceUla abortus. In addition to this the influence of different media, temperature, vitamins, heavy metal salts, etc., will be discussed. Five different strains of Penicillium notatum, here called PEN 1, 2, 3, 4, 5, have been investigated; all strains with the exception of PEN 42 were obtained from Dr. S. A. Waksman's collection.' Cultivation of those five strains on different solid media shows slight divergencies in growth, pigment and spore formation, etc.; on liquid media, all 5 strains show different production of antibacterial substances, PEN 2 being the most active in this respect, followed by PEN 6 and then PEN 4. Those three strains also showed distinctly the secretion of two different antibacterial substances. The other strains, producing less antibacterial substance, were not further investigated. Most of the experiments were carried out with PEN 2.