Résumé:
In our work, we conducted a study to produce a biosurfactant with a hyper power of
solubilization of oil and hydrocarbons contaminating the soil, this biomolecule was derived
from a bacterial strain isolated from a marine sediment contaminated by hydrocarbons (
fishing port of Khemisti, wilaya of Tipaza). Olive oil and ammonium nitrate are used as the
sole source of carbon and nitrogen respectively for production in aerobiosis and under
agitation in batch mode at 30°C. The BS7 biosurfactant production evaluation parameters are
: oil displacement diameter (PDD), surface tension (TS) and emulsification index (E24%).
The results obtained after three days of incubation are : a DDP = 8 cm, a TS = 28.36 mN/m
and an E24 = 75%. We recovered the biosurfactant by two methods one is acid precipitation
followed by liquid-liquid extraction by ethyl acetate and the other is cold ethanol
precipitation, we obtained crude biosurfactant characterized by an extraction yield equal to
1g.L-1 and 1.2g.L-1 respectively from two extraction methods. We characterized our
biosurfactant BS7 by Fourier Transform Infrared (FTIR) spectroscopy, the observed bands
and peaks suggested the glycolipid nature of BS7.
The essential step in our work is the incorporation of biosurfactant BS7 in an environmental
application, precisely in the remobilization of oil contaminating the ground, the work has
been done and the results are promising from the preliminary study with an elimination of
86% engine oil contaminating the sand compared to distilled water which only removed
30.34% of the contaminant. According to these remarkable results, the crude biosurfactant
was applied to a Saharan soil in the Hassi Messaoud region actually contaminated by
hydrocarbons, the results of FTIR on the treated soil show a remobilization of petroleum
identified by the vibrations of the C-H bonds of the groups methylenes and methyls,
quantification by gas chromatography coupled mass spectrometer GC/MS confirmed the
previous results and that the biosurfactant of strain S7 showed a remobilization efficiency of
hydrocarbons 1.3 times greater than the chemical surfactant (Tween 80). In this respect, the
use of S7 biosurfactant in the environmental field is certainly promising.
