[P008] Poster

1:00 PM - 1:50 PM JST(4:00 AM - 4:50 AM UTC)

[P04-598] Sustainable Phototactic Harvesting for High-Purity Biomass Production in Chlamydomonas reinhardtii

○Yukyoung Lee¹, Hae Lim Lee¹, Minju Cho¹, Jihee Jeong¹, Young Joon Sung¹ (1. Sookmyung Women’s University (Korea))

Keywords:

Chlamydomonas reinhardtii,Phototactic harvesting,Additive-free recovery,Semi-continuous cultivation,Scalable bioprocess

Microalgae-based bioprocesses represent a sustainable production platform, yet efficient harvesting remains a critical bottleneck for industrial commercialization. Conventional methods, including centrifugation and flocculation, are often energy-intensive or require exogenous chemical additives that compromise biomass quality, restricting their use in high-value applications. To address these challenges, we developed an additive-free harvesting strategy by exploiting the natural phototactic behavior of Chlamydomonas reinhardtii. Optimal positive phototaxis was successfully induced under low-intensity blue light (470 nm) at 3.52 µmol photons m^-2 s^-1. Using this light as the sole driving force, directed cell migration was successfully integrated into a semi-continuous cultivation system. This approach ensures stable biomass recovery over 12 consecutive cycles without any degradation in productivity or cellular health. Notably, cumulative biomass production showed an approximately 1.3-fold increase compared to the control, demonstrating superior process stability and enhanced production efficiency. Unlike traditional flocculation, which often compromises cell viability over repeated cycles, our phototactic process ensures residue-free, high-purity biomass. This approach is particularly suited for value-added industries with stringent purity requirements, such as pharmaceuticals, nutraceuticals, and functional foods. Furthermore, the scalability of this method was validated in a 50 L system, where a distinct cell-enriched layer formed rapidly within 40 minutes. These findings demonstrate that phototactic harvesting offers a practical, energy-efficient alternative to conventional processes, providing a clear technical path toward sustainable microalgae biorefineries.