Studies on Streptomyces lavendulae.

Since the isolation of streptothricin by Waksman and Woodruff in 1942 from a strain of Streptomyces lavendulae, numerous reports have appeared concerning the ability of different actinomycetes to produce this antibiotic or closely related compounds. In most of the antibiotic screening programs, streptothricin and streptothricinlike substances are among the first to be commonly encountered as products of cultures of actinomycetes grown on different media. In most cases these cultures are found to belong to the S. lavendulae group. Since only little attention has been paid to the morphology and cultural characteristics of various members of this group of organisms, first isolated and described by Waksman and Curtis in 1916, a detailed examination of its properties was undertaken. The identity of S. lavendulae is established easily by the characteristic lavender coloration of its aerial mycelium, although occasionally white mutants are obtained, and by the production of soluble brown to black pigments in organic media. Antibiotic-producing strains of this organism give rise to a variety of mutants, which differ morphologically, culturally, andphysiologicallyfrom theparent culture; variants free from aerial mycelium are unable to produce streptothricin (Waksman and Schatz, 1945). Some of the strains of S. lavendulae possess marked capacity to produce a number of closely related antibiotics (Hutchison, Swart, and Waksman, 1949); others may form mixtures of antibiotics, such as streptomycin and streptothricin (Trussell, Fulton, and Grant, 1947).