Simultaneously measuring carbon uptake capacity and chlorophyll a fluorescence dynamics in algae
Jason Hupp, Johnathan I.E. McCoy, Allen J. Millgan, Graham Peers
Abstract
Measurements of cellular carbon assimilation and chlorophyll a fluorescence are key tools for assessing the physiological capacity of algae and cyanobacteria. The uptake of CO2 from the immediate environment informs a researcher about photosynthetic rates. Chlorophyll a fluorescence dynamics can be used to infer efficiencies about light energy harvesting efficiencies and loss processes such as the loss of energy as heat through non-photochemical quenching. Here we report the utilization of novel instrument that continuously measures CO2 exchange from an aqueous solution to suspended cells synchronously with chlorophyll fluorescence. We apply the instrument to investigate the response of photosynthesis to increasing light in 3 different productive strains of eukaryotic microalgae. We found that the carbon assimilation rates of Scenedesmus obliquus (UTEX393) did not saturate, even in light fluxes approximating full sunlight. Monoraphidium sp. (26BAM) had a high nonphotochemical quenching capacity in excess light. Both of these strains, and a third, Scendesmus actus (LRBOY07), demonstrated remarkably linear relationships between carbon assimilation rates and relative electron transport estimates at lower light intensities. This work shows the utility of novel instrumentation to quickly assay the photosynthetic capabilities of microalgal strains.