title: Development of auxotrophy by streptomycin-resistant mutation.
abstract: Several streptomycin-resistant mutants of Escherichia coli have been isolated which require exogenous isoleucine for growth. The majority of these strains were of streptomycin-dependent phenotype. If grown in the absence of streptomycin, these streptomycin-dependent auxotrophs (Sm(d-aux)) strains were unable to produce beta-galactosidase and aldolase activities and also failed to exhibit donor properties in conjugation. Genetic analysis indicated that the isoleucine requirement of these strains could be caused by a mutation at the strA locus.
mesh_terms: D003227:Conjugation, Genetic; D003433:Crosses, Genetic; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005634:Fructose-Bisphosphate Aldolase / Q000096:biosynthesis; D005696:Galactosidases / Q000096:biosynthesis; D005796:Genes; D007532:Isoleucine / Q000378:metabolism*; D009154:Mutation; D011995:Recombination, Genetic; D013307:Streptomycin / Q000494:pharmacology*
chemical_list: D007532:Isoleucine; D005696:Galactosidases; D005634:Fructose-Bisphosphate Aldolase; D013307:Streptomycin