Role of low-level alternating current and impedance for enhancing microalgae biomass and lipid production

Microalgae hold significant potential for producing value-added bioproducts in pharmaceutical, cosmetic, food, and biofuel industries, with a global market value estimated at US$ 11.8 billion in 2023. Innovations in culturing systems, such as electric stimulation, aim to enhance growth performance, as it can improve cellular processes, including nutrient uptake and lipid accumulation. This study investigates the effect of low alternating electrical currents (μA) on the growth and lipid production of the halotolerant microalga Dunaliella salina across varying salt concentrations (3.5 % and 8.5 % Conway medium). Applying electric stimulation at 50, 750, and 990 μA for 30 min daily over 15 days resulted in significant enhancements, particularly at 3.5 % salinity, where lipid content increased by 144 %. The findings indicate that electrical stimulation notably reduced the lag phase and increased exponential growth rates, with superior growth coefficients correlating with higher medium impedance rather than direct current levels.