Environmental pollution with petroleum and petrochemical products such as diesel and used oils
has been recognized as one of the most serious current problem in the world, especially in developing
countries. These petrochemical products devastate the soil, surface and underground waters
and alter the microbial population at the polluted sites. Thus, the present work aims to optimize
the biodegradation of diesel and two used oils (SAE 40 and SAE 50) by bacterial strains
namely Acinetobacter S2 and Pseudomonas S7 using either nutrient factors (yeast extract, peptone
or trace elements) or surfactants (tween 80 or Sodium Dodecyl Sulfate: SDS). The strains are incubated
alone or together with the used oils or diesel supplemented or not with nutrient factors
or surfactants for 14, 28, 42 and 56 days, respectively. For all the incubation period, the hydrocarbons
degradation rates are determined by gravimetric assay. The results obtained show that
nutrient factors increase significantly SAE 50 used oil biodegradation (p = 0.009). Similarly, tween 80 increases SAE 50 and SAE 40 used oils biodegradation but not diesel one. The results also show
a significant difference between biodegradation rates at 14, 28, 42 and 56 days for all the hydrocarbons
tested (p

Biodegradation, Hydrocarbon, Nutrient Factor, Surfactant, Bacterial Strain