shows the values of ST measured on
the culture medium with time. Notably, the lowest ST of extra-
cellular biosurfactant (29.2 ± 0.3 mN/m) was reached at 20 h of
fermentation and no significant changes (p > 0.05) were observed
until the end of fermentation (29.8 mN/m) meaning that CMC was
reached after that time. The slight increment in ST values observed
after 51 h could be due to the biosurfactants began to be consumed
by the microorganism as substrate. Compared to the previous
experiment, it could be observed that a faster decrease of ST and a
better result (28.2 mN/m at 6 h) was obtained using a lower initial
biomass concentration (0.33 g/L).