Metabolic System for Starch Utilization in Vibrio parahaemolyticus

Abstract

Vibrio parahaemolyticus utilizes some polysaccharides, such as starch, dextrin, and glycogen, as the carbon and energy sources. Production of extracellular amylase seemed to be essential for utilizing these polysaccharides, because an amylase-deficient (Amy-) mutant, strain 3102, of the organism failed to utilize them. The maltose-negative (Mal-) mutants, strains 3131 and 3132, were also found to be unable to utilize the polysaccharides. This indicates that the utilization is ultimately performed through the metabolic pathway for maltose.
The amylase production was induced by starch, dextrin, or maltose present in the medium. However, the induced activities in the Mal- mutants were markedly different from those in the wild-type strain. The specific activity obtained with strain 3131 was about 2.5 times higher than that obtained with the wild-type strain, whereas the activity of strain 3132 was about 7% of that of the wild-type strain. All these findings strongly suggest that maltose is the inducer for the synthesis of amylase in this organism.