Nourseothricin sulfate (Streptothricin sulfate) is a broad-spectrum antibiotic that destroys the outer membrane of Gram-negative bacteria and is a dominant selective marker for Fonsecaea pedrosoi. Nourseothricin sulfate inhibits protein biosynthesis in prokaryotic cells and strongly inhibits the growth of eukaryotes like fungi and can also be used as a elective marker for a wide range of organisms including bacteria, yeast, filamentous fungi, and plant cells.