Effect of salinity stress on growth, lipid productivity, fatty acid composition, and biodiesel properties in Acutodesmus obliquus and Chlorella vulgaris

Abstract

Two microalgae strains including Chlorella vulgaris and Acutodesmus obliquus were grown on BG11 medium with salinity stress ranging from 0.06 to 0.4 M NaCl. Highest lipid content in C. vulgaris and A. obliquus was 49 and 43% in BG11 amended with 0.4 M NaCl. The microalgal strains C. vulgaris and A. obliquus grow better at 0.06 M NaCl concentration than control condition. At 0.06 M NaCl, improved dry biomass content in C. vulgaris and A. obliquus was 0.92 and 0.68 gL, respectively. Stress biomarkers like reactive oxygen species, antioxidant enzyme catalase, and ascorbate peroxidase were also lowest at 0.06 M NaCl concentration revealing that both the microalgal strains are well acclimatized at 0.06 M NaCl concentration. The fatty acid composition of the investigated microalgal strains was also improved by increased NaCl concentration. At 0.4 M NaCl, palmitic acid (37%), oleic acid (15.5%), and linoleic acid (20%) were the dominant fatty acids in C. vulgaris while palmitic acid (54%) and stearic acid (26.6%) were major fatty acids found in A. obliquus. Fatty acid profiling of C. vulgaris and A. obliquus significantly varied with salinity concentration. Therefore, the study showed that salt stress is an effective stress that could increase not only the lipid content but also improved the fatty acid composition which could make C. vulgaris and A. obliquus potential strains for biodiesel production.

Effect of iron and magnesium addition on population dynamics and high value product of microalgae grown in anaerobic liquid digestate

“…Moreover, C20:3 disappeared at the iron concentrations of 3.1 and 4.5 mM, which indicates that different iron concentrations could affect the composition of the fatty acids and can be effectually altered by changing iron concentrations. Since the unsaturation grade affects the cold flow, stability and ignition quality of diesel fuel 26 , C18:3 amount was limited as <12% (w/w) by European biodiesel standard EN14214 29 . According to the results from this study, C18:3 amount was measured between 1.3-3.1%, which examined the high quality of the biodiesel ( Table 1).…”

Large-Scale Cultivation of Spirulina for Biological CO2 Mitigation in Open Raceway Ponds Using Purified CO2 From a Coal Chemical Flue Gas

“…DIC concentration in the culture medium can be increased by adding NaHCO 3 (Nayak et al, 2018), which will increase in salinity due to Na + accumulation. However, excessively high salinity inhibits the growth of microalgae (Pandit et al, 2017); thus, an optimal range of NaHCO 3 should be controlled. As shown in Table 3, the CO 2 fixation rates of both strains were significantly higher at 0.1 mol L −1 DIC than at other inorganic carbon concentrations, suggesting that this DIC concentration is optimal for both strains in this study.…”

Chlorella vulgaris, a microalgae important to be used in Biotechnology: a review

“…Because the lipid content in the microalgae is within a range of 20 to 50% of the dry weight in the biomass generated, it is considered an important source for the generation of biodiesel, however, it is estimated that the operating costs and generation of this fuel are up to 10 times greater than those generated by obtaining crude oil, since the nutrients necessary for the growth of the microalgae are expensive (He et al, 2013), so it is convenient to optimize growth due to the effect of other factors, such as: the light, the temperature or the inorganic carbon source available to the microalgae, and even the use of media with nutritive loads that can be reused by these micro-organisms, such as those contained in wastewater. In previous investigations the growth of C. vulgaris has been evaluated under nutrient limitations and even under saline stress, where it has been observed that in those media where there is a saline concentration (NaCl) around 0.06 M to 0.4 M, the percentage of the lipid content in the biomass can reach a concentration of 49% at the highest salt concentration, and where there was an increase in the concentration of palmitic acid (37%), oleic acid (15.5%) and linoleic acid (20%) making this generated profile suitable for biodiesel production (Pandit et al, 2017).…”