New tools for Euglena: detection of paramylon and chlorophyll by flow cytometry

Euglena gracilis is a single celled flagellate protist that has garnered industrial interest due its production of paramylon, a crystalline β-1,3-glucan which has been found to have numerous medical properties and potential as a beneficial source of dietary fibre. Traditional biochemical methods of quantifying paramylon have been used extensively but are time consuming and low-throughput.Fluorescence-based methods provide a powerful alternative platform for detection of compounds and screening of desirable strains. The aim of the current research was to develop a method to fluorescently label intracellular paramylon granules in E. gracilis and explore the use of flow cytometry(FCM)to monitor paramylon content and chlorophyll content in E. gracilis cells during cultivation. Paramylon granules were labelled with the aniline blue dye and assessed via fluorescence and confocal microscopy, and FCM was implemented for high-throughput detection. Novel fluorescent labelling of intracellular paramylon granules was achieved and FCM was successfully utilised for the monitoring of paramylon, chlorophyll and metabolic state of E. gracilis during cultivation. Flow cytometry shows promise for algal research and is presented here as a novel tool for detection of paramylon content and monitoring of metabolic state in E. gracilis, opening new possibilities for the development of Euglena Biotechnology.