| Title | Application of high-salinity stress for enhancing the lipid productivity of Chlorella sorokiniana HS1 in a two-phase process |
|---|---|
| Author | Ramesh Kakarla1, Jung-Woon Choi1, Jin-Ho Yun2, Byung-Hyuk Kim3, Jina Heo1,4, Sujin Lee1,4, Dae-Hyun Cho1, Rishiram Ramanan5, and Hee-Sik Kim1,4* |
| Address | 1Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Republic of Korea, 2Department of Chemical and Biomolecular Engineering, KAIST, Daejeon 34141, Republic of Korea, 3Research Institute of Climate Change and Agriculture, National Institute of Horticultural and Herbal Science, RDA, Jeju 63240, Republic of Korea, 4Environmental Biotechnology, University of Science & Technology, Daejeon 34113, Republic of Korea, 5Department of Environmental Science, Central University of Kerala, Padannakkad Campus Kasaragod District, India |
| Bibliography | Journal of Microbiology, 56(1),56–64, 2018, |
| DOI | 10.1007/s12275-018-7488-6 |
| Key Words | Chlorella sorokiniana HS1, high-salinity stress, lipid induction, microalgae, two-phase process |
| Abstract | Increased lipid accumulation of algal cells as a response to environmental stress factors attracted much attention of researchers to incorporate this stress response into industrial algal cultivation process with the aim of enhancing algal lipid productivity. This study applies high-salinity stress condition to a two-phase process in which microalgal cells are initially grown in freshwater medium until late exponential phase and subsequently subjected to high-salinity condition that induces excessive lipid accumulation. Our initial experiment revealed that the concentrated culture of Chlorella sorokiniana HS1 exhibited the intense fluorescence of Nile red at the NaCl concentration of 60 g/L along with 1 g/L of supplemental bicarbonate after 48 h of induction period without significantly compromising cultural integrity. These conditions were further verified with the algal culture grown for 7 days in a 1 L bottle reactor that reached late exponential phase; a 12% increment in the lipid content of harvested biomass was observed upon inducing high lipid accumulation in the concentrated algal culture at the density of 5.0 g DW/L. Although an increase in the sum of carbohydrate and lipid contents of harvested biomass indicated that the external carbon source supplemented during the induction period increased overall carbon assimilation, a decrease in carbohydrate content suggested the potential reallocation of cellular carbon that promoted lipid droplet formation under high-salinity stress. These results thus emphasize that the two-phase process can be successfully implemented to enhance algal lipid productivity by incorporating high-salinity stress conditions into the pre-concentrated sedimentation ponds of industrial algal production system. |