Abstract:Coccomyxa subellipsoidea C-169 was cultivated outdoors in raceway open ponds using Basal medium, Bold’s Basal medium (BBM), and medium without adding nitrogen (N), and phosphorus (P). Comparisons were made across the three culture conditions in terms of cell-specific growth rate, biomass concentration, as well as content of fatty acids and pigments. The results showed good growth of Coccomyxa subellipsoidea C-169 at temperatures ranging from 13 ℃ to 20 ℃ in outdoor open ponds. During stage II, cells were in logarithmic phase after eight days of cultivation in Basal medium and BBM with limited N and P, where cell-specific growth rate in Basal medium was 1.92 times that in BBM and maximal biomass was 0.22 g/L. Linolenic acid content in the cells cultured in Basal medium and BBM accounted for 36.6% and 53.9% of total fatty acids, respectively, during stage I. However, during stage II, the proportion of linolenic acid content of total fatty acids in the cells cultured in Basal medium, with N and P limitations decreased by 32.4%, while that of oleic acid increased by 38.5%. In BBM containing low N and P concentrations, the content of total fatty acids increased from 3.99% to 18.18%. In stage III, cells were cultivated for five days in a 1:1 mixture of Basal medium and BBM. During stage III, average growth rate of cells decreased to 0.0094 d-1, total fatty acid content in biomass increased to 20.2% dry weight, and pigment content decreased with increasing fatty acid content, showing a significant negative correlation.
