Influence of nourseothricin on growth and secondary metabolism of Streptomyces noursei JA 3890b

The nourseothricin-producing S. noursei strain JA 3890b possessed a high degree of resistance to its own antibiotic when grown in submerged cultures started from mycelium samples as inocula. In contrast, both the outgrowth of spores and the development of surface colonies from mycelium samples were severely inhibited in the presence of relatively low concentrations of nourseothricin, suggesting that the producer organism is susceptible to the autotoxic metabolite in particular stages of its development. Nourseothricin production by submerged cultures has been found to be independent of negative feedback regulation by the antibiotic.