Selecting Bacterial Mutants by the Penicillin Method

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Science  26 Feb 1960:
Vol. 131, Issue 3400, pp. 604-605
DOI: 10.1126/science.131.3400.604


Certain improvements are described in the use of penicillin for isolating auxotrophic mutants of bacteria. By obtaining exponential growth before the penicillin is added, and by minimizing the duration of the treatment, cross-feeding is decreased and much denser populations can be screened. These modifications have made it possible to obtain, with regularity, mutants of Escherichia coli blocked in a desired step in arginine biosynthesis.