cAMP-mediated catabolite repression and electrochemical potential-dependent production of an extracellular amylase in Vibrio alginolyticus

Vibrio alginolyticus, a halophilic marine bacterium, produced an extracellu lar amylase with a molecular mass of approximately 56,000, and the amylase appeared to be subject to catabolite repression mediated by cAMP. The produ ction of amylase at pH 6.5, at which the respiratory chain-linked H+ pump f unctions, was inhibited about 75% at 24 hours following the addition of 2 m u M carbonyl cyanide m-chlorophenylhydrazone (CCCP), while the production a t pH 8.5, at which the respiratory chain-linked Na+ pump functions, was onl y slightly inhibited by the addition of 2 mu M CCCP. In contrast, the produ ction of amylase in a mutant bacterium defective in the Na+ pump was almost completely inhibited even at pH 8.5 as well as pH 6.5 by the addition of 2 mu M CCCP.