PHOTOLITHOTROPHIC CULTIVATION OF LAMINARIA-SACCHARINA GAMETOPHYTE CELLS IN A BUBBLE-COLUMN BIOREACTOR

The photolithotrophic cultivation of a novel cell suspension culture d erived from the microscopic, filamentous gametophyte life phase of the complex brown alga Laminaria saccharina was feasible in an illuminate d bubble-column bioreactor at 13 degrees C using CO2 in air as the sol e carbon source for growth. Maximum cell densities exceeding 1,000 mg dry cell weight (dcw) l(-1) and specific growth rates of 0.15 day(-1) were attained within a 20-day cultivation period initial cell density had a significant effect on the final biomass density of the clumped c ell suspension but no significant effect on the specific growth rate. Although the optimum aeration rate for culture growth was 1.0 l air mi n(-1) l(-1) culture (vvm), the culture was not CO2-transport limited a t 0.17-2.0 vvm. initial nitrate concentrations at or above 63.5 mg NaN O3 l(-1) in the GP2 artificial seawater medium had no significant effe ct on the specific growth rate or final biomass density. Both specific growth rate and final biomass density data were correlated to inciden t light intensity over the range of 1-91.2 mu E m(-2) s(-1) using an e xponential model for light-saturated growth where light-saturated grow th was achieved within a low-incident light intensity of 20 mu E m(-2) s(-1).