BACTERIAL 5'-NUCLEOTIDASE ACTIVITY IN ESTUARINE AND COASTAL MARINE WATERS - CHARACTERIZATION OF ENZYME-ACTIVITY

We measured 5'-nucleotidase by following the hydrolysis of ATP and measured alkaline phosphatase by conventional fluorometric techniques. 5'-Nucleotidase (5PN) was found in all estuarine and coastal marine waters where measurements were made, regardless of the degree of eutrophication or phosphate concentrations. Its activity was usually concentrated in the bacterial size fraction. 5PN was competitively inhibited only by 5'-nucleotides and was distinguishable from alkaline phosphatase by both this substrate specificity and the lack of inhibition by low concentrations of orthophosphate. The percent of uptake of orthophosphate regenerated by 5PN was inversely related to the ambient phosphate concentration.