1. Induction constants (K(ind)) and repression constants (K( @entity70493 )), which are a measure of the affinity of the inducers or repressors for the induction systems, were measured for @entity19832 , @entity10555 and @entity16366 in @entity15250 . 2. From these results, the enzymic response of the organism to media containing pairs of these substrates was predicted. @entity1568 -limited chemostats, operated at high growth rates, were used to investigate these predictions in cells grown first on one aromatic substrate with the second added later. 3. In general, the values of K(ind) and K( @entity70493 ) predicted quite accurately the response to substrate mixtures. Thus, in the presence of mandelate and either @entity10555 or @entity16366 , the enzymes of mandelate metabolism were repressed almost completely, and the bacteria were fully induced for the alternative substrate ( @entity10555 or @entity16366 ), which was preferentially utilized for growth. When @entity10555 and @entity16366 were the two substrates in the mixture, the enzymes for metabolism of the latter were strongly repressed and growth took place mainly on @entity10555 . 4. The enzymic response to mixed substrates did not result in the metabolism of the better growth substrate, but in the substrate requiring the synthesis of fewer enzymes. Thus @entity10555 is used in preference to mandelate although the latter supports a faster growth rate. It is nevertheless considered that, with our present knowledge of the natural habitat of the organism, it is impossible to decide whether protein economy or growth rate was the factor determining the evolution of this control system.

Regulation of pathways degrading aromatic substrates in XXXX . Enzymic response to binary mixtures of substrates.

@entity1568 :: ('MESH:D009584', 'Chemical') :: ['Nitrogen'] @entity15250 :: ('303', 'Species') :: ['Pseudomonas putida'] @entity16366 :: ('MESH:C038193', 'Chemical') :: ['p-hydroxybenzoate'] @entity19832 :: ('CHEBI:25147', 'Chemical') :: ['mandelate'] @entity70493 :: ('3974187(Tax:303)', 'Gene') :: ['rep'] @entity10555 :: ('MESH:D001565', 'Chemical') :: ['benzoate']
@entity15250 :: (303,Species) :: ['Pseudomonas putida']
