Enhanced lipid selective extraction from Chlorella vulgaris without cell sacrifice

Abstract

This study examines the performance of biocompatible organic solvents for lipid milking without cell sacrifice utilizing microalgal cells up to four cycles. Simultaneous production and extraction, is an integrated process of milking that involves cultivation of C. vulgaris under the influence of dodecane and tetradecane within the aqueous-organic biphase system and the extraction of intracellular lipids. Different concentrations (10% v/v, 15% v/v, and 20% v/v) of dodecane and tetradecane were used for the extraction of lipid. The highest lipid amount (1175 ± 34 mg/L) within the solvent phase was achieved with maximum lipid recovery ratio of 47 ± 5% during first cycle when 20% concentration of dodecane was used as the solvent. In addition maximum cell dehydrogenase activity (4.5 ± 0.5 OD492 g− 1 cell) and growth rate (1.8 d− 1) were also observed under 20% dodecane. The presence of higher concentration of tetradecane lowers the dehydrogenase activity thus resulting in lower lipid extraction under milking. Solvent recovery ratio was 12% higher under 20% dodecane as compared to 10% of tetradecane. Growth profile study of C. vulgaris showed an overall increase in the lipid content when the cultures were extended up to four cycles. The analyzed fatty acid composition suggests that this technique could yield lipids that are suitable for conversion to biodiesel. According to the present results, a hypothetical scheme of milking technique under biocompatible organic solvents is proposed.