Enhanced lipid productivity of Chlamydomonas reinhardtii with combination of NaCl and CaCl2 stresses

• Published in: Bioprocess and biosystems engineering Vol. 43; no. 6; pp. 971 - 980
• Main Authors: Hang, Le Thai, Mori, Kazuhiro, Tanaka, Yasuhiro, Morikawa, Masaaki, Toyama, Tadashi
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2020; Springer Nature B.V
• Subjects: Abiotic stress; Accumulation; Acyltransferase; Algae; Biotechnology; Calcium chloride; Chemistry; Chemistry and Materials Science; Chlamydomonas reinhardtii; Combinatorial analysis; Diglycerides; Environmental Engineering/Biotechnology; Food Science; Glycerol; Glycerol-3-phosphate; Glycerol-3-phosphate dehydrogenase; Industrial and Production Engineering; Industrial Chemistry/Chemical Engineering; Lipids; Lysophosphatidic acid; Microalgae; Productivity; Research Paper; Salts; Sodium chloride; NaCl; CaCl; Lipid accumulation; Biofuel production
• DOI: 10.1007/s00449-020-02293-w
• ISSN: 1615-7591

Salinity (NaCl) stress treatment is a strategy to induce lipid accumulation in microalgae. This study aimed to investigate the effect of a combination of two salts (NaCl/CaCl 2 ) on lipid productivity of Chlamydomonas reinhardtii . C. reinhardtii was cultured in a two-stage culture comprising 9-day active growth in C medium followed by 3-day salt stress in C medium with various concentrations of NaCl (50‒200 mM)/CaCl 2 (100 mM). In salt stress stage, NaCl (200 mM), CaCl 2 (100 mM), and the NaCl/CaCl 2 mixture inhibited growth but increased the lipid content in C. reinhardtii in comparison with NaCl (0, 50, and 100 mM) conditions. Combinatorial treatment with 100 mM NaCl/100 mM CaCl 2 resulted in the highest lipid content (73.4%) and lipid productivity (10.9 mg/L/days), being 3.5- and 2.1-fold, respectively, in salt-free control conditions, and 1.8- and 1.5-folds, respectively, with 200 mM NaCl. Furthermore, 100 mM NaCl/100 mM CaCl 2 treatment markedly upregulated glycerol-3-phosphate dehydrogenase ( GPDH ), lysophosphatidic acid acyltransferase ( LPAAT ), and diacylglycerol acyltransferase ( DAGAT ), which are involved in lipid accumulation in C. reinhardtii . The upregulation of these genes with 100 mM NaCl/100 mM CaCl 2 resulted in the highest lipid content in C. reinhardtii . Therefore, stress treatment using two salts, 100 mM NaCl/100 mM CaCl 2 , is a potentially promising strategy to enhance lipid productivity in microalgae.