title: Selection of thymine-requiring strains from Escherichia coli on solid medium.
mesh_terms: D000630:Aminopterin / Q000494:pharmacology; D003470:Culture Media; D004926:Escherichia coli / Q000254:growth & development / Q000302:isolation & purification*; D009154:Mutation; D013941:Thymine / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D003470:Culture Media; D000630:Aminopterin; D013941:Thymine