1995 but were in fact growing with little or no induction until the glucose was depleted and only then being induced by the lactose present in the medium a comprehensive series of tests including time courses of growth and induction under different conditions were consistent with this interpretation the term auto induction is used to refer to the growth pattern of inducible expression strains in inducer containing media where growth is essentially normal in the early stages with little or no induction and expression of the target protein is turned on automatically at a later stage of growth with no intervention much of the testing to define the auto induction behavior and the factors affecting it was done with target protein p21 of a structural genomics project a well induced not particularly toxic protein yeast peptide chain release factor subunit 1 expressed under control of a t7lac promoter in a pet vector in b834 de3 which also contained a compatible plasmid expressing trnas for rare arginine isoleucine and leucine codons the results may be summarized as follows little growth was apparent in simple salts media containing lactose as sole carbon source presumably because the level of induction was too high to allow growth addition of increasing.