A culture filtrate of a streptomyces inhibited growth of S. aureus 209 P on a semisynthetic medium, Knight medium, but exhibited no inhibition against this organism growing on a nutrient agar. This active substance was isolated and crystallized as the calcium salt and the identity with PA 147, 3-carboxy-2, 4-pentadienal lactol reported by Els, Sobin and Celmer¹⁾ was confirmed. This antibiotic was found to have inhibitory activity against HeLa cells and ascites and solid forms of Ehrlich carcinoma.

Characters of the streptomyces producing PA-147 has not been described. In this paper, characters of the strain producing this antibiotic and production, isolation, and properties of the antibiotic are presented.