Paramylon, a starch-like carbohydrate accumulated in Euglena gracilis cells, could be a potential source as a raw material for chemical products; its high-yield production would thus be highly desired. Although the molecular weight and polymerization degree of paramylon are important properties for its use as a raw material for chemical products, the available information about paramylon molecular weight remains insufficient. Therefore, in this study, we investigated a high-density E. gracilis culture approach and how culture conditions affect paramylon molecular weight. The nitrogen source, cultivation temperature, and nutrient feeding were optimized for maximum biomass and paramylon productivity. The maximum dry cell weight and paramylon content yields reached 108.9 g/L and 87.2%, respectively. Paramylon molecular weight was in the range of 220 000-320 000 Da. Our gel permeation chromatography analysis showed that the cells with a higher paramylon content tended to contain paramylon of a higher molecular weight.
Keywords: Euglena gracilis; molecular weight; paramylon.
© The Author(s) 2023. Published by Oxford University Press on behalf of Japan Society for Bioscience, Biotechnology, and Agrochemistry.