The Effect of Linoleic Acid and Nanoparticle Treatments as Inducers on Biomass and Fatty Acid Content in the Microalga, Haematococcus lacustris

Increased biomass density of microalgae is a critical factor in the enhancement of the algal metabolites. In this study, the effects of linoleic acid, TiO2, and SiO2 nanoparticles were investigated as elicitors on the production of biomass, and fatty acids in the microalga, Haematococcus lacustris. Several treatments of TiO2 and SiO2 nanoparticles were analyzed as well as linoleic acid on Haematococcus lacustris in two separate designs. Microalgal biomass in nanoparticles was investigated using the Neobar chamber and in linoleic acid using the freeze-dryer methods. Fatty acids compositions were tested by gas chromatography method and five of them named Palmitic, Palmitoleic, Stearic, Oleic, and Linoleic acids (LA) were measured. The results showed that the biomass significantly increased by LA (30 μM) and TiO2NPs (40 mg/L) treatments, and consequently, these treatments increased the biomass density by 2 and 1.3 times more than the control treatment, respectively. Palmitic and linoleic acids were the most frequent fatty acids produced by 60 and 30µM of LA treatments with 1.4 (53.26 % w/w) and 1.5 (32.51 % w/w) folds, respectively. To conclude, the different concentrations of LA and TiO2NP boosted the production of algal biomass, and some fatty acids in Haematococcus lacustris. Moreover, LA may be used as an effective inducer to increase biomass production in the valuable microalga Haematococcus lacustris.