A strain of Pseudomonas sp. was isolated from activated sludge, growing on a mineral medium with benzylpenicillin as the sole carbon source. During growth the phenylacetate side chain was degraded and utilized. The nucleus molecule of the antibiotic, 6-aminopenicillanic acid, was not used but hydrolysed to penicic acid. Cell-free extracts contained β-lactamase and penicillin acylase activities.
