At the end of experiment, hydrocarbon content of the alga strain was estimated. The results showed that the alga cultivated in aerated swine lagoon wastewater accumulated 23.8% hydrocar- bon, which was similar to our previous report when 10–20% CO2 was used to aerate the same alga strain (Ge et al., 2011). For the alga cells cultivated in BG11 medium, the average hydrocarbon content was only 11.9%. This might be resulted from the relatively high nitrogen of BG11 medium (1500 mg L