Penplasmic aminopeptidase and alkaline phosphatase activities in a marine bacterium- implications for substrate processing in the sea

The occurrence of periplasmic aminopeptidase and alkaline phosphatase (APase) was studied in a Gram-negative bacterium (designated S8) isolated from the surface waters off the Southern California coast. We tested the hypothesis that processing of polymeric substrates (e.g. protein) by marine bacteria involves ectohydrolases both on the cell surface and in the periplasmic space but small substrates (e.g. sugar phosphates) are hydrolytically processed only in the periplasm.