Nourseothricin (streptothricin) inactivated by a plasmid pIE636 encoded acetyl transferase: nature of the inactivated nourseothricin.

Nourseothricin, a mixture of several streptothricins, is inactivated by an acetyl transferase produced by Escherichia coli containing the plasmid pIE636. Nourseothricin inactivated in the presence of 14C-acetate was purified and submitted to partial hydrolysis. In the hydrolysate besides others a radioactive and ninhydrin-reactive substance moving only slightly towards the cathode was found. It proved to be [14C]-acetyl beta-lysine.

Antiviral antibiotic S15-1. Taxonomy of the producing strain and study of conditions for production of the antibiotic.

Strain S15-1 which produces antiviral antibiotic S15-1 belonging to the streptothricin group of antibiotics was isolated from a soil sample. Cell analysis, colony morphology, the absence of sporangia-like vesicles, the formation of spores in chains of the Rectus Flexibilis type, and the ability to produce melanoid pigment, indicate that this strain belongs to the genus Streptomyces Waksman and Henrici. A comparison of the characteristics of strain S15-1 with related Streptomyces show that it should be identified as Streptomyces purpeofuscus Yamaguchi and Saburi. The investigation of cultural conditions show that soluble starch and meat extract are the most suitable carbon and organic nitrogen sources for the production of antibiotic S15-1. Strain S15-1 grew poorly on media with no organic nitrogen sources, and did not produce the antibiotic. Antiviral antibiotic S15-1 is accumulated at the highest level after 3 or 4 days growth of the producing organism.