Flow cytometry and cell sorting in marine phytoplankton research: Redefining measurements per cell

Flow cytometric techniques are applied to re-examine per cell quotas of carbon and chlorophyll in marine phytoplankton. Axenic cultures of Dunaliella sp. and Phaeodactylum sp. are light and nutrient stressed. Sub-samples of 2.5 x 10 super(4) cells which satisfy stringent criteria of low angle light scatter (cell size) and pigment autofluorescence are sorted and retrieved for subsequent bulk analyses. Changes in fluorescence per unit chlorophyll, carbon and chlorophyll per cell, and carbon to chlorophyll ratio as a function of light intensity and nutrient stress are discussed. A brief description of the Coulter Electronics EPICS V flow cytometer and cell sorter is included.