High-Throughput Microfluidic Platform for Real-time Investigation of Lipid Droplet Accumulation in Microalgae

Abstract

Microalgae offer great promise to contribute a significant portion of the renewable fuels that is required by the Renewable Fuels Standard. Algal biofuels is based mainly on the high lipid content of the algal cells and thus would be an ideal feedstock for high energy density transportation fuels, such as biodiesel, green diesel, green jet fuel and green gasoline. With high lipid productivity of dominant, fast-growing algae is a major prerequisite for commercial production of microalgae oil-derived biodiesel. However, under optimal growth conditions, large amounts of algal biomass are produced, but with relatively low lipid contents. Meanwhile, species with high lipid contents are typically slow growing. Currently, the single cells observation and quantification of lipid accumulation after the stationary growth phase under various stress conditions is still a challenge. To solve this issue, we have conducted the microfluidic platform to investigate the development of lipid droplet in individual microalgae, Chlamydomonas reinhardtii by immobilizing monolayer cells on the glass surface coated with gelatin. In addition, our novel platform able to eliminate the absorption of BODIPY fluorescence into the polydimethylsiloxane (PDMS) microchannel and also the media can be changed easily. In the end, the lipid droplet accumulation was observed in-real-time at the single cell resolution under different conditions of light and nutrient, allowing the correlations among lipid trigger conditions and lipid production, as evidenced with BODIPY 505/515 fluorescence lipid staining. Keywords: Microalgae, Microfluidic, Single cell immobilization, Lipids accumulation, Real–time observation, Glass-PDMS sandwich device