Lipids were determined in biomass harvested by filtration (Whatman No:1) and washed with distilled water. The wet biomass was dried at 70 oC overnight. The dried biomass was extracted in a centrifuge tube using 20 mL of hexane, homogenized with a basic ultraturrax (IKA LABORTECHNIK, Staufen, Germany) for 5 min, kept in a water bath at 55 oC for 10 min and centrifuged at 936g for 10 min. The supernatant was transferred to another centrifuge tube. The extraction was repeated twice using 10 mL of hexane, and the supernatant was collected and evaporated using a vacuum rotary evaporator at 45 oC for 10 min. The dried biomass and lipids were measured with an analytical balance (Dong and Walker, 2008).