CULTIVATION OF SACCHAROMYCES-CEREVISAE IN A BIOREACTOR IN MICROGRAVITY

Yeast cells were cultured for 8 d in a newly developed bioreactor duri ng the Spacelab IML-2 mission. Two bioreactors, one stirred and one wi thout stirring, were installed in the Biorack facility in space. Two c ontrol units were installed in the Biorack module at the Kennedy Space Center. Samples were drawn on mission day 3, 5, 6, 7 and 8 and preser ved either by freezing or chemically fixed for post-flight analysis. T he values of pH, pH regulation, temperature and redox potential were t ransmitted on-line to the ground station throughout the mission. The p erformance of the bioreactor was satisfactory except for a partial fai lure of the medium micropump. Despite the failure of the pump, the dat a support the following conclusions: There is a significant difference in the distribution of the bud scars between cells cultured at 0 x g and at 1 x g, The percentage of randomly distributed bud scars was sig nificantly higher in the flight (17%) than in the ground control cells (5%). No remarkable differences were noted in the cell cycle, ultrast ructure, cell proliferation, cell volume, ethanol production and gluco se consumption.