Evaluation of Lipid composition and growth parameters of cold-adapted microalgae under different conditions

Abstract

Abstract In the current study, Cheshmeh-Sabz Lake located in northeastern Iran (36°20’N, 59°3’ E) with an average minimum annual temperature of -15˚C was screened to isolate native cold-adapted microalgae strains. Various isolation and purification methods (different freshwater culture media at 5 ºC, liquid serial dilution with streak plate methods, and then fluorescence-activated cell sorting) were used to find dominant cold-adapted microalgae strains. Three cold-adapted microalgae growth parameters (Scenedesmus sp., Ankistrodesmus sp., and Chlorella sp.) were investigated at 8 ºC and 25 ºC. Among isolates, Scenedesmus sp. (dominant in BG-11) had the same and relatively high biomass productivity (~ 0.54 ± 0.001 g L−1 d−1) at low and high temperatures. Fatty acid profile evaluation of three species at 8, 15, and 25 ºC indicated, the highest amount of α-linolenic acid was produced in Scenedesmus sp., and there was no significant difference between the amount of α-linolenic acid at 15 ºC and 25 ºC (10.96 ± 1.5% and 11.07 ± 0.31%, respectively). There were no significant differences between palmitic acid amount at 8, 15, and 25 ºC (41.05 ± 5.2, 38.48 ± 4.25, 39.82 ± 1.58% respectively) in Scenedesmus sp. Based on the results, Scenedesmus sp. is the proper choice for outdoor cultivation in different seasons due to its relatively high biomass productivity and the specific growth rate in low and high temperatures (8, and 25 ºC). In addition, the good ability of polyunsaturated fatty acids production (~27%) and rich in saturated fatty acids at low and high temperatures (~ 66%) makes this species susceptible to work in the biofuels field and feed supplements.