Microfluorimeter for Studying the State of Photosynthetic Apparatus of Individual Cells of Microalgae

Abstract—A fundamentally new microfluorimeter is designed to assess the functional state of primary photosynthesis in individual phytoplanktonic cells. The device is tested during a sea expedition. It allows estimation of the amount of photosynthetic pigments, the primary photosynthetic efficiency, the light slope of the linear electron-transfer rate (light response curve) as well as the degree of nonphotochemical quenching of excited pigment molecules in every cell found in a studied phytoplankton community. This data enables plotting of the distribution diagrams of algal cells for each of the listed characteristics within the population of every algal species. The microfluorimeter has a convenient graphic interface where a user can save the measurement results to spreadsheets. The detection limit of the device is equal to 1 pg of chlorophyll inside the photometric volume. This sensitivity is high enough for the reliable quantification of chlorophyll-fluorescence parameters of individual algal cells. The microfluorimeter is equipped with a system that maintains the object temperature constant over a wide temperature range limited from below by the dew point and water condensation on the cover-glass surface.