Abstract
Optimal nitrate, phosphate and salinity for maximal biomass, lipid and carotenoid content of the freshwater microalga Kirchneriella obesa were investigated by using Box-Behnken Design. In an optimised condition, these three factors enhanced biomass production by 0.64 g/L more than the control (0.25 g/L). At 2.5 g/L nitrate, 0.04 g/L phosphate, and 25 mM NaCl, the maximum lipid accumulation (46.02%) and carotenoid content (2.58 mg/L) were achieved. The fit of the model yielded R2 values of up to 0.9955 for biomass, 0.9984 for lipids and 0.9999 for carotenoid, respectively. For the highest carbohydrate (418.28 mg/L) content, the medium was supplemented with 1.5 g/L nitrate, 0.04 g/L phosphate, and 40 mM NaCl. While the highest protein content (320.53 mg/L) was attributed to the medium with 3 g/L nitrate, 0.02 g/L phosphate and 25 mM NaCl. The major fatty acid compositions found in this algae were C18:1trans (16.36 ± 1.4), C18:1cis (6.001 ± 0.44), C18:2 (8.32 ± 1.1) and C18:3 (34.39 ± 2.3%), demonstrating their importance in biofuel production and human health.
Acknowledgement
The authors are also thankful to the Central Sophisticated Instrument Facility (CSIF), University of Calicut for epi-fluorescence analysis.
Disclosure statement
No potential conflict of interest was reported by the authors.