Isolation of antibiotic‐sensitive mutants of Azotobacter chroococcum by treatment with ascorbic acid

A mutant of Azotobacter chroococcum sensitive to penicillin and novobiocin was isolated by treatment with 2 m mol l−1 ascorbic acid. Presence of ascorbic acid was found to stimulate the inhibitory effect of both the antibiotics in A. chroococcum Mac 27 and its mutant Mac 27 (671) ; however, the effect was more pronounced in mutant Mac 27 (671). The mutant strain Mac 27 (671) did not produce β‐lactamase, a property which was present in the strain Mac 27.