The sensitivity of the dinoflagellate Crypthecodinium cohnii to transient hydrodynamic forces and cell-bubble...

The increased interest in the benefits of omega-3 fatty acids for human health has resulted in the commercial development of the dinoflagellate Crypthecodinium cohnii for production of docosahexaenoic acid (DHA). The growing market demand for DHA requires highly efficient, very large scale cultures of DHA. While the effects of hydrodynamic forces on dinoflagellates have been investigated for several decades, the majority of the work focused on the negative effects of oceanic turbulence on the population growth of environmentally important dinoflagellates. In contrast, significantly less is known on the effect of hydrodynamic forces encountered by algae in bioprocesses. Unlike other studies conducted on algae, this study employed a microfluidic, flow contraction device to evaluate the effect of transient hydrodynamic forces on C. cohnii cells. It was found that C. cohnii cells can sustain the energy dissipation rate of 5.8 x 10(7) W/m3 without lysis. However, an obvious sublethal effect, the loss of flagella, was observed at a lower level of 1.6 x 10(7) W/m3. Finally the cell-bubble interaction and the effect of bubble rupture were also explored to simulate the conditions of sparged bioreactors.