The effects of elevated CO₂ concentrations on changes in fatty acids and amino acids of three species of microalgae

ABSTRACT

Microalgae are important producers in aquatic ecosystems and are valuable for biodiesel production and feed supply industries. Three such microalgae, Nannochloropsis oceanica (Eustigmatophyceae), Dunaliella salina (Chlorophyceae), and Chlamydomonas reinhardtii (Chlorophyceae), were cultured at two pCO₂ (400 ppm, 1000 ppm) to investigate changes in fatty acid and amino acid composition. Elevated pCO₂ increased C16:0, C18:3, C20:5, total saturated fatty acid (SFA), total polyunsaturated fatty acid (PUFA), and total essential amino acid (EAA) content in N. oceanica. High CO₂ concentration reduced C16:0 and total SFA content, but increased C18:3, total PUFA, and total EAA accumulation, in D. salina. Changes in C. reinhardtii were the opposite of those in D. salina. Results indicated that higher pCO₂ may improve the quality of biodiesel produced by N. oceanica and C. reinhardtii. Furthermore, in N. oceanica and D. salina, increased CO₂ concentration elevated nutrient levels but resulted in reduced nutrient quality in C. reinhardtii. Our results can help predict nutritional changes in microalgae at elevated pCO₂, and provide insight into production of biodiesel and animal feed by microalgae.

KEYWORDS:

• Amino acid
• Carbon dioxide
• Chlamydomonas reinhardtii
• Dunaliella salina
• Fatty acid
• Nannochloropsis oceanica

Additional information

Funding

This work was supported by the National Key Research and Development Program of China (Grant numbers 2018YFD0900703, 2018YFD0901503); and the National Natural Science Foundation of China (Grant number 31770393).