The effects of elevated CO<sub>2</sub> concentrations on changes in fatty acids and amino acids of three species of microalgae
Chengwei Liang, Lu Wang, Yufei Zhang, Jian Zhang, Xiaowen Zhang, Naihao Ye
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.