Microfluidic droplet cultivation preserves microalgae diversity in screening systems

Efficient screening of microalgae is critical for their research and industrial applications. However, conventional methods of microalgae screening are often considered inefficient and are applicable to a narrow range of species. We conducted a proof-of-concept study on the applicability of a water-in-oil droplet (WODL)-based microfluidic system to high-throughput screening of microalgae and effect of microfluidic droplet cultivation on the species diversity within microalgal samples. First, we confirmed that microalgae with diverse morphologies could be successfully cultured within droplets. Second, we conducted culture tests using a mock community derived from monocultured microalgal strains and a field community derived from the natural environment. Subsequent long-read metabarcoding targeting the 16 S rRNA gene, followed by diversity analysis, revealed that droplet culture is more effective than bulk mixed-species culture in maintaining species diversity. Our results lay the groundwork for the future development of WODL-based high-throughput screening systems, allowing access to a richer microalgal biodiversity.