A strategy for control of light intensity in suspension culture of photoautotrophic liverwort cells, Marchantia Paleacea var, Diptera

A suspension culture of photoautotrophic liverwort cells, Marchantia paleacea var. diptera, was carried out at 25 degrees C in a bioreactor with external light irradiation. It was found that a series of incident light intensities to maximize the cell growth rate along with change in the concentration of the cells existed, based on the calculation in terms of the distribution of light intensity and the dependency of cell growth rate on light intensity in the bioreactor. In the batch culture of M. paleacea cells using the bioreactor, incident light intensity was controlled in the range of 30 to 122 W/m(2), the values of which were adequately determined by the calculation according to given concentrations of the cells during the culture. In the culture associated with the light intensity control, the amount of the cells obtained at 312 h was 5.1 kg dry cell weight per unit volume of medium, and this value was 1.7 and 6.9 times as large as the amounts of the cells obtained at 312 h in the reference cultures at constant incident light intensities of 30 and 180 W/m(2), respectively. Among the cultures under these conditions of incident light intensities of 30 to 122, 30 and 180 W/m(2), a remarkable reduction in chlorophyll contents was observed in the cells cultivated at 180 W/m(2).