CULTIVO DE Saccharomyces boulardii EM BIORREATOR AIR-LIFT E EM FRASCOS AGITADOS MECANICAMENTE

Abstract

Air Lift Fermenters offer advantages such as efficient homogenization of the components, low shear stress, and energy savings, since the medium is stirred by the process of aeration, without the need for mechanical stirring. The goal of this work was to evaluate the growth kinetic of S. boulardii yeast (probiotic) in an Air-lift reactor, with aeration conditions of 1 and 1.5 air vvm (air volume/medium volume/minutes), comparing this with their growth in mechanically stirred flasks, with a view to future industrial application of this fermenter. A decrease in pH was observed, with the uptake of glucose in the medium, which was completely consumed, up to the end of the exponential phase (5h and 6h for the stirred flask and Air-lift, respectively). After this period, there was an alteration in the speed of growth of S. boulardii, for both types of equipment, suggesting a possible change in the carbon source used, since all the glucose was consumed after these periods. During the exponential phase, the values of specific growth speeds were similar for the stirred flask and the Air-lift fermenter, with 1.0 vvm (0.350 h-1 and 0.351 h-1, respectively), however, these values were lower than the Air-lift 1.5 vvm (0.382 h-1), indicating, in the case of the latter, that it may be possible to achieve a higher cell production speed, depending only on the efficiency of the oxygenation offered. The formation of ethanol was observed during the exponential phase, which appears to be used as a source of carbon after the end of the primary substrate (glucose), with a consequent decrease during the linear growth phase (7-12 h), which supports the hypothesis that this metabolite is being used as a source of carbon in a diauxic glucose-ethanol process.