Enhancing lipid production in Chlorella under successive stresses of periodic micro-current and salinity: Performance and contribution

Two-stage cultivation of Chlorella with periodic micro-current coupled with NaCl stress was investigated to analyze the performance and contribution of increased lipid production. In the growth stage, periodic micro-current of 3 mA resulted in an escalation of 290.06 mg/L of Chlorella's biomass by 61.25 % in comparison to the control. During the induction stage, under a NaCl concentration of 8 g/L, the highest lipid content and yield attained were 42.11 % and 199.32 mg/L, revealing an increment of 53.13 % and 39.11 % respectively when compared to the control. Additionally, the polyunsaturated fatty acids content (PUFA) decreased from 30.11 % to 23.09 %, while the saturated fatty acids content (SFA) increased from 31.86 % to 42.39 %. Chlorella demonstrated adaptability to the alterations in the cultivation environment by an initial upsurge and later a reduction in SOD and CAT enzyme activities, and concurrently facilitated lipid synthesis by similar changes in the activities of ACCase and DGAT. The above cultivation enabled a synergistic effect of swift growth and efficient lipid accumulation in Chlorella, providing groundwork for large-scale biofuel production.