As we were searching strains for penicillin, two strains of Penicillia, antagonistic against both gram negative and positive bacteria,
were isolated from the air and their antibacterial substance was purified up to the colourless plate crystals. Afterwards we could also extract the same substance from three other strains of Penicillia isolated by other workers in Japan and sent to our labolatory, and also from Aspergillus clavatus.
In publication by Bergel and others (1) the chemical, physical, biological properties of Patulin, Clavatin and Claviformin and their identity were described. As the properties of the antibacterial substance obtained by us are similar to Patulin and it is extracted, not only from five strains of Penicillia but also from Aspergillus clavatus, it is highly probable that the substance obtained by us is identical with Patulin. After the publication of our work in Japanese (January, 1946), Kuroya informed us that he had also extracted the same substance from a strain of Penicillium. This substance has been obtained K from many strains isolated from various places, so it must be widely distributed in nature.