A perfusion-cell bleeding culture strategy for enhancing the productivity of eicosapentaenoic acid by Nitzschia laevis

A perfusion-cell bleeding culture strategy was developed for enhancing the productivity of eicosapentaenoic acid (EPA) by the diatom Nitzschia laevis. As the strategy combined the concepts of continuous culture and perfusion culture, it allowed continuously and simultaneously harvesting the algal ce lls and removing inhibitory compounds during the cultivation. Compared with a single operation of continuous culture, the perfusion-cell bleeding cult ure greatly enhanced the steady-state biomass concentration, biomass produc tivity, EPA yield, EPA productivity and glucose utilization efficiency. The perfusion-cell bleeding culture also allowed higher biomass productivity a nd EPA productivity than the single perfusion culture did. At a bleeding ra te of 0.67 day(-1) and a perfusion rate of 0.6 day(-1), the EPA productivit y achieved 175 mg l(-1) day(-1), which is the highest ever reported in micr oalgal cultures.