Molecular responses of phospholipids of Taxus cuspidata (Japanese yew) to hydrodynamic shear stress in bubble columns

Molecular responses of phospholipids of Taxus cuspidata (Japanese yew) cells to hydrodynamic shear stress were investigated by using two bubble columns with different nozzle sizes. T. cuspidata cells cultured in bubble columns responded with an increase in cell membrane permeability when compared with shake-flask culture, corresponding to the alteration of phospholipid constitutions. Phospholipid differences between bubble columns and shake-flask cultures were analysed by using LC/ESI (liquid chromatography/electrospray ionization)-MS coupled with PCA (principal component analysis). It was found that PA (phosphatidic acid) is the main molecular species of potential biomarkers. The amount of PA was found to increase, whereas PC (phosphatidylcholine) and PI (phosphatidylinositol) decreased after 96 h of cultivation in bubble columns, corresponding to the obvious increase in membrane permeability after 96 h of culture in such columns. A decrease in the nozzle size of the bubble column led to a more significant difference in phospholipids. These results suggest that PA accumulation plays an important role in the membrane degradation induced by hydrodynamic shear stress.