Effect of mixtures of substrates on the biosynthesis of inducible enzymes in Aerobacter aerogenes.

Previous investigations in this laboratory have dealt with the striking effect of glucose on the induced biosynthesis of three enzyme systems in Aerobacter aerogenes (Magasanik, 1955; Neidhardt and Magasanik, 1956a). During the course of these studies it was found that glucose is not the only substance whose inclusion in a growth medium restricts induced enzyme biosynthesis, although it is unique in exerting a near-complete inhibition. The magnitude of these non-glucose effects occasionally reaches a 75 per cent inhibition of enzyme biosynthesis. Such inhibitions have been frequently noted by other workers (Monod, 1947; Gale, 1943) but no investigations have been made of their mechanism. The work reported in this paper was undertaken to study these inhibitions and to diseover the relationship, if any between them and the "glucose effect."