The effect of salinity stress on the growth and lipid accumulation of Scenedesmus quadricauda FACHB-1297 under xylose mixotrophic cultivation

In the commercial production of microalgae biodiesel, high culture cost and low lipid production yields are two major limitations. Finding cheap carbon sources and ways to promote lipid accumulation can achieve low-cost cultivation and efficient lipid production. The impact of NaCl on the growth and lipid accumulation in Scenedesmus quadricauda FACHB-1297 under xylose mixotrophic cultivation was explored in this study. The results showed that when NaCl concentration were 0.88–5.85 g/L, the biomass concentration and lipid content were 2.15–2.68 and 1.19–1.80 times higher than those in BG11 medium, respectively. Under the optimal NaCl concentration of 2.63 g/L, the highest lipid content (39.33%) was achieved, with the biomass concentration of 0.72 g/L, the total nitrogen removal efficiency of 39.00%, and the total phosphorus removal efficiency of nearly 100.00%, except for a higher total sugar content of 19.26% and total protein content of 5.38%. In short, these results indicated that 2.63 g/L NaCl treatment was an efficient way to promote the lipid accumulation of S. quadricauda FACHB-1297 using xylose in papermaking waste liquid to produce biofuel.