Rapid and Accurate Quantification of Paramylon Produced from Euglena gracilis Using an ssDNA Aptamer

The functional ingredients of microalgal biomass are receiving substantial recognition as the global demands for health supplements produced from natural sources are on the rise. Paramylon, a conglomerate of β-1,3-glucans, is one of the major valuable sources derived from Euglena gracilis having multiple applications, thus necessitating the development of an efficient quantification method. Here, we employed a DNA aptamer to quantify the amount of paramylon produced by E. gracilis. Paramylon-specific aptamers were isolated by the systematic evolution of ligands by exponential enrichment (SELEX) process. To evaluate the potential aptamers, the binding affinity between aptamer candidates and paramylon granules was confirmed by a confocal laser scanning microscope and the dissociation constants of the selected aptamers were determined by nonlinear regression analysis. The selected DNA aptamer was successfully used for the quantification of paramylon, and the results were compared to those obtained by the standard methods. The new approach was also used for quantification of paramylon from E. gracilis cells cultured to different cell stages and physiologies. It can be concluded that the aptamer-based protocol for the measurement of paramylon proposed in this study is highly accurate and comparatively less time-consuming.