Our earlier studies revealed that urea was a suitable nitrogen source for cultivation of Chlorella sp. Y8-1. Urea was adopted into the medium at 0–2 g/L. The biomass, specific growth rates, and
lipid content of Chlorella sp. Y8-1 in the stationary phase are shown in Fig. 4. The cultures had a low biomass concentration, specifi growth rate, and lipid content in the N-free medium. The Chlorella sp. Y8-1 grew the most robustly in the medium containing 0.1– 0.25 g/L of urea, reaching a biomass concentration of