Stimulating the Growth of Chlorella Microalgae Using Ultrasound

The study investigated the effect of ultrasonic radiation on the growth of Chlorella microalgae cells and the accumulation of intracellular metabolites (intracellular water-soluble proteins, lipids) in them. The results of the study showed that daily ultrasonic radiation (72 J/ml) with a power of 300 W for 60 s had a significant positive effect on the growth rate of microalgae. Increasing the ultrasound power from 20 W (4.8 J/mL) to 300 W (72 J/mL) resulted in a 1.3-fold increase in cell concentration in suspension and 1.4-fold increase in biomass concentration after 24 days of cultivation. The positive effect of ultrasound treatment on the process of periodic cultivation of microalgae is attributed to the acceleration of metabolism due to the increase in temperature of the suspension and the destruction of extracellular phenolic metabolites that inhibit the nitrate-anion transport system. In addition, ultrasound has a positive effect on the accumulation of intracellular metabolites in the biomass (the concentration of intracellular water-soluble proteins and total lipids became 1.4-fold and 2-fold higher, respectively, compared to the control). The research aims to increase the efficiency of the cultivation stage and may have practical significance for microalgae producers and researchers involved in the development of new methods to improve the production and obtain valuable substances from microalgae.