Co-culture process: in the shaking trials, the initial cells of R. glutinis and S. obliquus were inoculated into the flask to achieve the initial cell density of 6.00 •10^5 cells/ml and 4.90•10^6 cells/ml co-culture medium. The mixed cultures were cultivated for 4 days at 24 C, 150 rpm, with light intensity of 100 mol m-2 s-1. In the 5L photobioreactor trials, the agitation rate would be fixed at 150 rpm and 1 vvm of aeration, with 98% air,2% CO2 provided and with light intensity of 100 mol m-2 s-1. All of the experiments were carried out at least in triplicate.