Antibiotic Substances from Basidiomycetes

Abstract

Discs cut from an agar culture of P. griseus produced a clear zone of inhibition on plates seeded with Staphylococcus aureus. Tests with 5. aureus resistant to other antibiotics (including penicillin) indicate the presence of a new antibiotic. P. griseus was grown on several media and in liquid culture. By chloroform extraction from the latter and the removal of acids, a gum was left. This was recrystallized, and the physical properties of this "Pleurotin" are reported. Lack of thermostability, and low solubility in water suggest that possible therapeutic value is unlikely. Pleurotin was active only on Gram-positive bacteria. A single dose was not toxic to mice. Pleurotin showed some inhibition of Mycobacterium tuberculosis. A 2d anti-bacterial substance may be formed by P. griseus, for discs cut from a colony gave zones of inhibition larger than discs saturated with Pleurotin. The acid fraction showed some activity.