Protein synthesis inhibitory activity in culture filtrates from new strains of Streptomyces isolated from Brazilian tropical soils

Aims: To investigate the effect of the culture supernatants from three newly isolated Streptomyces strains, 221, 235 and 606 on eukaryotic cells. Methods and Results: Cell lines were treated with the culture filtrates and assayed for protein synthesis by metabolic labelling, followed by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis analysis. RNA synthesis was investigated by [5‐3H]uridine incorporation. The three culture filtrates presented a strong inhibitory activity, reducing total protein synthesis of different eukaryotic cell lines by more than 85%. No effect on cellular RNA synthesis was detected. The culture filtrates did not affect the growth of the prokaryotic cells tested. Conclusions: These new Streptomyces strains, recently isolated from Brazilian tropical soils, produce molecule(s) with inhibitory activity specific to eukaryote protein synthesis. Significance and Impact of the Study: Streptomyces strains 221, 235 and 606, probably representing new species, might produce new bioactive compound(s), and can be used as valuable tools to study the protein synthesis pathway in eukaryotes.