Finally,the measure ofthe ST in water containing the cell-bound
biosurfactants showed a reduction in ST from 54.5 mN/m at time 0
to 37.8 mN/mafter 6 hbeing almost constantfrom11 huntil achieving a lowest level of 32 mN/m after 51 h. ST results of cell-bound
biosurfactant are slightly superiors to those achieved in the previ-
ous experiment with smaller amount of initial biomass, where the
lowest ST (30 mN/m) was achieved at 52 h of fermentation. These
results seem contradictory, since having more biomass should have
more cell-bound biosurfactant since the metabolite is found inside
or attached to the cells. It is feasible that during fermentation this
cell-bound biosurfactant became extracellular due to shear in the
bioreactor