I-11, a new antibiotic. Taxonomy of the strain I-11, isolation, fermentation, biological activity and chemical characterization of the antibiotic produced.

A new antibiotic I-11, was isolated from the mycelial cake of strain I-11, an antibiotic-producing microorganism isolated from soil samples collected in the vicinity of Madras, India. The strain exhibits several modes of growth that differ from those of the Streptomycetes and Actinomycetales, but similar to certain fungi'). Strain I-I1 grows fairly well on all of the media employed according to the ISP criteria outlined by GOTTLIEB and SHIRLING2). Unless otherwise stated, the experiments to determine the cultural characteristics were carried out at 28.5°C for 13•` 15 days in a pH environment between 7 and 8. The gelatin stab culture was observed after incubation at room temperature for 18 •` 20 days. Microscopic examination of the culture on an inorganic salts starch agar revealed thick, closely