2.1. Microorganism
In this present study, a biosurfactant producing microorganism, identified as Pseudomonas sp. AJ15, was selected to perform the experiments on the basis of its plant growth promoting traits and ability to degrade petroleum oil.
This strain was isolated from petroleum oil contaminated soil and stored in our laboratory.
The inoculum was prepared by transferring a loopful of bacterial cultureinto 25 ml nutrient medium (composition g/l beef extract-3 g, peptone-5 g, NaCl-5 g) in 250 ml Erlenmeyer flask and incubated at 30 C for 24 h. This inoculum contained 108 cells/ml.