PS-5, a new .BETA.-lactam antibiotic. I. Taxonomy of the producing organism, isolation and physico-chemical properties.

Antibiotic PS-5 is a new beta-lactam antibiotic isolated from fermentation broths of Streptomyces sp. strain A271. The strain was considered to be a new subspecies of Streptomyces cremeus and the name, Streptomyces cremeus subsp. auratilis, was proposed. Fermentative production, isolation and physico-chemical properties of PS-5 are described.