A method for determining alkaline phosphatase activity in marine phytoplankton using spectrofluorometry

A method for determining relative percent intensity alkaline phosphatase activity (APA) using enzyme labeled fluorescence coupled with spectrofluorometry is presented. Compared to traditional microscopy and flow cytometry, we increase statistical power and reduce sample-handling issues. Combined with a biological standard, our method can quantify APA of natural plankton assemblages.

► We determine phytoplankton alkaline phosphatase activity by spectrofluorometry.
► Statistical output is increased with spectrofluorometry.
► Spectrofluorometry measurement is effective for cultured and natural populations.
► We conduct method inter-comparison with microscopy and flow cytometry.
► Spectrofluorometry is better than microscopy at determining labeling intensity.