Many antibiotics have been obtained from streptomyces, yet, numerous antibiotics effective only to Gram-posltive bacteria seem to have been left without sufficient study. A strain which was isolated from the garden soil collected at Meguro, Tokyo, in summer 1947, and produced an antibiotic to Gram-positive bacteria, was found to be particular among antibiotic streptomyces in its morphological and biological characters. The spore chains in clusters, the strong nitrate reducing effect and the hydrolysis of cellulose were characteristic. Therefore, the species of this strain was denominated asS. nitrosporeus. The antibiotic which was extracted and purified was different from the ones already described and named as nitrosporin.
In the present paper, the study on the antibiotic, nitrosporin, is described, and the taxonomic study of the strain will be described in the other paper by okami of our laboratory.