title: Procedure for isolating mutants defective in metabolite transport or utilization.
abstract: Mutants defective in uptake or utilization of a given metabolite can readily be obtained from facultative auxotrophs (for that metabolite) by penicillin enrichment under nonpermissive conditions in the presence of a low level of the required metabolite.
mesh_terms: D001120:Arginine / Q000378:metabolism; D001693:Biological Transport, Active; D002250:Carbon Radioisotopes; D003470:Culture Media; D004926:Escherichia coli / Q000302:isolation & purification* / Q000378:metabolism; D007532:Isoleucine / Q000378:metabolism; D009153:Mutagens; D009154:Mutation; D009604:Nitrosoguanidines; D010406:Penicillins; D011392:Proline / Q000378:metabolism; D013696:Temperature
chemical_list: D002250:Carbon Radioisotopes; D003470:Culture Media; D009153:Mutagens; D009604:Nitrosoguanidines; D010406:Penicillins; D007532:Isoleucine; D001120:Arginine; D011392:Proline