Biosurfactants Production During Diesel Biodegranation by Mixed Microbial Consortia Selected From Polluted Spolls

This work studies the biosurfactants production which enables the diesel biodegradation by using mixed microbial consortia from polluted sites. It was carried out by culturing three microbial consortia (named as XA, XB and XC) obtained from polluted soils, and enriched in diesel as sole carbon source.Batch experiments were done to study the effects of three variables (temperature,hydrocarbon concentration and the origin of the consortia) on the diesel biodegradation and the surface tension evolution. The three enriched consortia contained similar bacterial genera and degraded diesel with similar efficiencies (approximately 90%). Thermal inhibition was observed at 35 ºC. The evolution of surface tension was similar in all experiments: an initial fast reduction followed by an increase once the diesel had been consumed. All three consortia were found to be efficient biosurfactants producers. Consortia XB and XC had similar low biosurfactant yields (1.3 and 1.8 g g-1, respectively) and lower critical micelle concentration values (0.42 and 0.45 g L-1, respectively), while XA generated a greater quantity of biosurfactants (6.9 gg-1). It was noted that the maximum diesel biodegradation rate increased versus the biosurfactants yields. Despite some differences between the consortia due to their different origins, especially concerning biosurfactants production, the diesel-enrichment process resulted in adapted consortia with similar efficiencies for diesel biodegradation.