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The aim of this study was to optimize the light regimes including initial inoculum density, photoperiod and light intensity on the growth and lipid (TAG) accumulation in Ankistrodesmus fusiformis H1 for biodiesel production. At last, the strategy of 4.47 mM urea with initial OD 680 -0.5, 18:6 h light/dark cycle and 200 μmol photon m −2 s −1 regimes were optimized. The lipid productivity of 116.88 mg L −1 d −1 and 57.58% neutral lipid in total lipid were achieved finally. Moreover, the changes of photosynthetic activity, pigments contents and biochemical compositions revealed that more carbon flow to lipid synthesis. Therefore, A. fusiformis H1 is an ideal candidate for biodiesel production by utilizing light appropriately. [ABSTRACT FROM AUTHOR]

NaCl induction in photoautotrophic two-step cultivation is very promising, but time node and concentration are critical to the entire production. In this study Monoraphidium dybowskii LB50 was subjected to different NaCl concentrations at different growth phases. Results showed that during the initial phase (IP), fixed carbon was used for sugar and lipid under 5 g L −1 NaCl induction, as well as for protein under 10 g L −1 NaCl induction. At late-exponential growth phase (LEGP), the highest lipid productivity was obtained at 20 g L −1 NaCl. At stationary phase (SP) the highest lipid productivity was also under 20 g L −1 NaCl but lower than that of LEGP. In summary, lipid content and quality were improved at all growth phases under NaCl induction. Therefore, cultivation scale can be sued to determine the time node and dosage of the inducer, thereby realizing the economic efficiency of the fundamental guarantee in photoautotrophic two-step cultivation. [ABSTRACT FROM AUTHOR]

Highlights: [•] 0.25gL−1 urea is the optima for biomass accumulation in D. abundans. [•] NaCl was outstanding of different salts (NaCl, NaHCO3, NaAc and NaS2O3) on lipid induction. [•] Higher lipid productivity was obtained during the optimized cultivation process. [•] 1.79gL−1 of biomass concentration was the time point for NaCl addition. [•] Strategy of NaCl addition for cultivating D. abundans was cost-efficient and net energy-positive. [Copyright &y& Elsevier]