Fluid motion mediates biochemical composition and physiological aspects in the green alga Dunaliella primolecta Butcher

Experiments were conducted in a laboratory bioreactor to study the effect of small-scale fluid motion on the composition of some key biochemical compounds and physiological processes of the microalga, Dunaliella primolecta Butcher. The bioreactor with submersible speakers generated nearly homogeneous and isotropic turbulence. Fluid flow was the only systematically controlled experimental variable, with other environmental conditions, including light intensity, temperature, initial salinity, and nutrient concentration, nearly similar during the experimental measurements. The growth, protein, and fatty acid accumulation of D. primolecta were enhanced by the moving fluid flow in the bioreactor. Over an 8-d experiment under turbulent fluid flow conditions, a twofold increase in cell number, chlorophyll, protein, and total fatty acid concentrations was observed in D. primolecta. Conversely, no significant increase in these variables was observed under stagnant fluid conditions. The results could have important implications for the design and operation of natural and engineered bioreactors under specified fluid flow conditions for efficient bioenergy production from microalgae.