A study was also conducted to determine whether the biodegradation
of diesel oil by this organism could be enhanced by the
addition of biosurfactant An6 in the culture media. Biosurfactant
An6, produced in Landy medium, was added to the flask cultures at
three different concentrations (0.5, 1 and 2 g/L) and degradation
was followed over 15 days. Degradation of oil was initially assessed
by visual observation of the medium. Flasks were found with tiny
oil droplets dispersed in the medium resulting in browning of the
medium. Gravimetric analysis of the residual oil was also done.
Biosurfactant An6 stimulates the biodegradation capacity of the
An6 strain in a concentration-dependent manner. Compared with
the biosurfactant-free inoculated culture, a significant increase of
the biodegradation efficiency of diesel oil by the An6 strain, of
approximately 15, 23 and 30% in the presence of 0.5, 1 and 2 g/L of
biosurfactant An6, respectively, was observed