Lipid content and fatty acid methyl ester profile by Chromochloris zofingiensis under chemical and metabolic stress

This work encompasses the effect of chemical and metabolic stress on lipid content and fatty acid methyl ester (FAME) profile by Chromochloris zofingiensis. To this aim, a control medium amended with specific concentrations of sodium chloride (15 g L-1, 30 g L-1, and 60 g L-1) and of ethanolamine (ETA) and triethylamine (TEA) (0.050 g L-1, 0.100 g L-1, and 0.150 g L-1) has been used for the cultivation of this strain. A better lipid content than the control was obtained under salt stress compared to chemical stress induced by ETA and TEA, while the effect on lipid productivity was negligible. Thirty grams per liter of NaCl allowed to obtain the highest value of the total lipid content (30.33% DW) compared to the control (20% DW). FAME profile revealed a 97.50-98.99% composition in C16-C18 with no statistically meaningful differences among the three concentrations of salt and chemicals tested. The most represented fatty acids were C18:1 oleic (> 45%wt), C16:0 palmitic (> 34%wt), and C18:2 linoleic (> 21%wt) obtained under 60 and 30 mg L-1 of NaCl and 0.150 g L-1 of ETA, respectively. When using 0.150 g L-1 of ETA, unsaturated fatty acids reached the highest portion (67.53%wt) than the control (62.26%wt). A quantitative and qualitative analysis of all FAMEs has been carried out to improve biodiesel properties. Chemical and physical properties of algal lipid-derived biodiesel showed a compliance with ASTM standards for unmixed biodiesel and the main European regulations (EN 14214 and EN 590) for the quality of biodiesel resulted fulfilled. Therefore, a profitable biodiesel can be obtained when cultivating C. zofingiensis under osmotic stress.

Automated summary

This study investigates the effects of salt and chemical stress on lipid content and FAME profile in Chromochloris zofingiensis. The results show that salt stress leads to higher lipid content compared to chemical stress, while the effect on lipid productivity is negligible.