Pruess, David L. (University of Wisconsin, Madison), and Marvin J. Johnson. Enzymatic deacylation of S(35)-benzylpenicillin. J. Bacteriol. 90:380-383. 1965.-S(35)-benzylpenicillin, penicilloic acid, and penilloic acid were deacylated by cell suspensions of Escherichia coli and Micrococcus roseus. Both cultures deacylated penicillin most rapidly and penilloic acid least rapidly. The deacylase activity of M. roseus against penicilloic acid was cell-bound, probably requiring a metal ion for activity.