which may be due to the microorganism starts consuming the metabolite. At each time surface tension reduction
(ST) was calculated as ST0–STt. The ST of CH culture medium
showed the highest value (ST = 59.5–27 = 32.5 mN/m), followed
by MSM + CH and HH + CH (ST = 55–27 = 28 mN/m) and MSM + HH
(ST = 54.3–27 = 27.3 mN/m). In all cases, ST was 27 mN/m at
day 1 of fermentation. The ST reduction for MSM + HH + CH was
26.8 mN/m. After one day, ST reached a minimum of 26.3 mN/m.
Considering these results, it can be inferred that the strain ZSB10
can use both cellulosic and hemicellulosic hydrolyzates to pro-
duce biosurfactants. In all prior cases, the surface tension reduction
was higher when MSM was used as culture broth for biosur-
factant production, because it only was observed a reduction of
-
ST = 50–32 = 18 mN/m. In all cases,the production of extracellular
biosurfactant was evidenced since a substance can be considered
as biosurfactant when added to distilled water is able to lower the
ST in more than 8 units