Effects of Salinity on Growth and Total Lipid Con-tent of the Biofuel Potential Microalga Ankistro-desmus falcatus (Corda) Ralfs

Growth responses and total lipid content of a native strain of the biofuel potential freshwater oleaginous microalgae A.falcatus was studied owing to its inherently high lipid content for potential utilization as renewable biomass feedstock of biofuels. Influences of salinity in increasing order from 40 mM to 320 mM of NaCl in BG11 medium on growth (μ), total lipid (TL) content and calorific value (CV) were studied in triplicate batch mode culture at light intensity 35 μmol/m 2 /s, temperature 25 ± 2 0 C and 16:8 hrs light and dark diurnal cycles. Enhanced growth and total lipid contents were observed with increasing salinity up to 160 mM NaCl. The highest specific growth (μ=0.313 d -1 ) and least doubling time (T2=2.21 days) with maximum increase in cell numbers (2.9 x 105 ml -1 ) were recorded in medium supplemented with 160 mM of NaCl compared to control medium (μ=0.209 d -1 , T2=3.32 days and 1.52 x 105 ml -1 respectively). Improved total lipid (55.3%), carbohydrate (14.5%), and protein (4.8%) contents were also determined compared to control medium (lipid 38.3%, carbohydrate 12.6%, and protein 3.1%, respectively). With maximum energy value of 27.9 ± 0.15 kJg -1 , a close correlation (R 2 = 0.955) between lipid content and calorific value was observed. With the support from present research findings, the native strain of freshwater oleaginous microalga A. falcatus could be a potent candidate for production of renewable biomass feedstock of biofuels. The present research findings will be supportive towards further culture optimization for increased biomass yield with concomitant lipid content and improved of fatty acid profile in mass cultivation.