Abstract
Penicillinase-deficient mutants were isolated from Kluyvera citrophila KY 3641 capable of carrying out enzymatic synthesis of 6-aminopenicillanic acid (6-APA) or D(-)-α-aminobenzy lpenicillin (APc). Acridine orange treatment was found effective for the isolation of such mutants, some of which could produce larger amounts of 6-APA or APc than the parent strain. Particularly during an earlier stage of growth, the penicillin acylase activity of these penicillinase-deficient mutants did emerge due to the absence of penicillinase, while that of the parent strain did not appear because of its penicillinase activity.
