Microalgae, unicellular photoautotrophic microorganisms, have attracted great attention for the production of biofuel and high-value products, but the commercial use of microalgae has been limited by low photosynthetic productivity. To overcome this limitation, it is required to develop an efficient platform for the rapid evaluation of photoautotrophic growth performance and productivity of microalgal strains. Here we describe a droplet-based photobioreactor for high-throughput analysis of the photoautotrophic growth of microalgal cells. By integrating micropillar arrays and adjusting the height of the microchamber, we could accurately monitor the growth kinetics of microalgae in an immobilized microdroplet and improve the transfer rate of CO2 into the microdroplet photobioreactor with an increased contact area between the microdroplet and PDMS surface. The improvement of CO2 transfer into the microdroplet was also confirmed by improved microalgal cell growth and a decrease in pH measured using colorimetric and fluorescence-based assays. The photoautotrophic growth kinetics of Chlorella vulgaris were measured under different CO2 concentrations (ambient, 1%, 2.5%, 5% and 7.5%) and light intensity (35, 55, 100, 150, and 200 μmol photons per m2 per s) conditions, which are key factors for photoautotrophic growth. Chlorella vulgaris in a microdroplet showed better cell growth performance compared to a flask culture due to the reduced shading effects and improved mass transfer. Finally, we could evaluate the photoautotrophic growth performance of four microalgal strains (Chlorella vulgaris, Chlorella protothecoides, Chlorella sorokiniana and Neochloris oleoabundans) for 120 hours. These results demonstrate that our microdroplet system can be used as an efficient photobioreactor for the rapid evaluation of the photoautotrophic growth of microalgal strains under various conditions.
Bibliographical noteFunding Information:
This study was supported by grants (2014M1A8A1049278) from Korea CCS R&D Center of the NRF funded by the Ministry of Science, ICT, and Future Planning of Korea, the National Research Foundation of Korea (NRF) grants (Grant No. NRF-2013R1A2A1A01015644/2010-0027955), the Korea Institute of Energy Technology Evaluation and Planning and Ministry of Trade, Industry and Energy of in "Energy Efficiency and Resources Technology R&D" project Korea (20152010201900) and University-Institute Cooperation Program (2013).
© The Royal Society of Chemistry 2016.
ASJC Scopus subject areas
- Analytical Chemistry
- Environmental Chemistry