Impact of cultivation parameters on astaxanthin accumulation in the green alga Haematococcus lacustris RRGK isolated from Himachal Pradesh, India

The unicellular, freshwater microalga Haematococcus lacustris is one of the finest microbial sources of astaxanthin, but when cultivated with conventional media it exhibits low growth rates and final densities. In this study, the effect of media, pH, light intensities, and various inorganic salts such as NaNO3, K2HPO4•3H2O, KH2PO4, and NaCl were investigated on the vegetative cells of Haematococcus lacustris RRGK (formerly H. lacustris HPI-001) isolated from Himachal Pradesh in India and H. lacustris SAG-19a procured from Gottingen Culture Collection, Germany. The latter served as the control. The isolate of H. lacustris RRGK recorded a maximum of 26.48 mg/L astaxanthin in 3N-BBM+V medium, 23.16 mg/L at 40.0 µEm−2s−1 light intensity, 21.85 mg/L at pH 7.5, 21.84 mg/L in 6.0 mM of NaNO3, 18.69 mg/L in 0.45 mM of K2HPO4•3H2O, 23.86 mg/L in 1.1 mM of KH2PO4 and 22.82 mg/L in 0.80 mM of NaCl. Based on the above-mentioned findings, a Modified HPI- 001A medium was formulated. A maximum production of algal biomass corresponding to a cell number of 53 × 104cells/mL and an astaxanthin content of 27.16 mg/L were documented in this novel media developed for improving growth and production of astaxanthin in H. lacustris RRGK under laboratory conditions.