Practice question

Complete medium provides rich mixture of yeast extract, peptone, all amino acids, vitamins and intermediates that circumvent any biosynthetic defect through external supply. Because required metabolites provided exogenously both prototrophs capable of synthesis and auxotrophs dependent on external supply grow luxuriantly without selection. This contrasts with minimal medium which selects only prototrophs capable of autonomous synthesis. Laboratory maintenance of auxotrophic collections uses complete medium before transferring replicas to minimal plates supplemented singly to identify specific nutritional requirement, standard strategy in Neurospora and E. coli genetics.