Cultural Conditions and Nutrient Composition as Effective Inducers for Biomass and Lipid Production in Fresh Water Microalgae

Autotrophic cultivation of microalgae induces low biomass and lipid production and is difficult to be used in pilot scale production.Heterotrophic and mixotrophic algae allows higher growth rate, which in turn can accumulate higher biomass and lipid.Enhanced biomass and lipid production is crucial to use oleaginous microalgae for industrial application of biodiesel production.A fresh water microalga was isolated from waste water treatment plant and identified as Scenedesmus obliquus.The isolate was grown under varying cultural and nutrient conditions to increase biomass and lipid production.For this purpose, CO 2 (10-160 mL minG 1 ), temperature (20-45°C), fructose, maltose, glucose, sucrose and starch (10-50 g LG 1 ), urea, sodium nitrate, potassium nitrate, ammonium nitrate and ammonium chloride (0.2-1.0 g LG 1 ) were used.Optimum conditions were found by calculating specific growth rate and used to determine their influence on biomass and lipid production.At 40 mL minG 1 (0.51%) CO 2 concentration, 18.17 g LG 1 biomass and 64.2% lipid production was obtained from the isolate.Glucose at 20 g LG 1 have produced 18.62 g LG 1 and 62.6% whereas sodium nitrate at 0.8 g LG 1 resulted in 14.64 g LG 1 and 65.1% of biomass and lipid production at the end of 20 days culturing period.Temperature of 25°C was found optimum where 12.38 g LG 1 and 60.9% of biomass and lipid were obtained.Based on the results, by choosing optimum cultural conditions and nutrient composition of the growth medium it is possible to increase both biomass and lipid production in microalgae.