Evaluation of fatty acid composition of the microalgae Choricystis minor var. minor according to two different nutrient feeding strategies

Abstract

The microalgae biomass, mainly rich in lipids, carbohydrates, and other groups of compounds, has been considered as a promising raw material for renewable fuels production, particularly biodiesel. However, further knowledge on this subject is still needed. The objective of this study was to evaluate the effect of culture growth conditions (nutrient fractionation) on the cell biomass levels, fatty acid profile, as well as the content of fatty acids methyl esters (FAME) of freshwater microalgae Choricystis minor var. minor. The experiment consisted in determining the culture growth (biomass levels) employing WC medium in two treatments: full initial addition (100%) and fractional addition of nutrients on three specific days. The biomass produced was harvested in the exponential and stationary phases of the growth curve. No significant differences were found in the biomass levels (approximately 0.5 g l−1 at 8 days of culture) using different treatments. The FAME yields varied between 213.7 and 276.8 mg g−1 of dry biomass. Regarding the qualitative composition, fatty acid profiles were similar under tested culture growth conditions, whereas the quantitative content changed between them. The results from this investigation suggested that cultivation with full initial nutrient addition and biomass harvested at the stationary phase provided higher FAME yield and lower tri-unsaturated fatty acids (9.6%) and polyunsaturated fatty acids (4.0%) levels. Because of these characteristics, this culture growth conditions represent, among the studied strategies, the most interesting for Choricystis minor var. minor cultivation in order to produce biodiesel.