A study was conducted on fresh water green algae Selenastrum sp. to check its growth behavior and tolerance under different concentrations of sodium bicarbonate salt, carbon dioxide gas and under different levels of sodium chloride salt. From the study it is clear that optimum levels of proper carbon source and salinity is very much essential for growing Selenastrum sp., as they influences its growth rate, biomass and lipid productivity. The experiment aims to analyze the biomass productivity and total lipid content of the microalgae strain under various growth conditions. All the cultures were grown for a period of 9 days. For the growth study, sodium bicarbonate salt concentrations in the range of 20, 40, 60, 80, 100 mg/L and CO2 concentrations of 4400, 5200, 7000, 7900 mg/L were selected and lastly NaCl salt in the range of 0.02, 0.04, 0.06, 0.08 & 0.17 Molar concentration were selected for the study. Maximum growth was observed at 60 mg/L concentration of bicarbonate salt, at which specific growth rate of 0.762/day, Increase in cells no of 2.078X104 cells/ ml/day, an increase in biomass of 1.102 mg/ml/day and an increase in total lipid 14% in dry cell weight was obtained. When CO2 gas was supplied at 5.2mg/L concentration, maximum growth and maximum lipid yield of 15 in %dry cell weight were recorded. A highest total lipid content of 19% was obtained when cells were grown under 0.02 Molar NaCl concentration.
