Isolation and Identification of Bacterial Strains
The bacterial strains used in this study were isolated by Berry et al. [29] from the soil contaminated by petroleum hydrocarbons. Some physicochemical and microbiological parameters to characterize soil were as follows (mean range): pH – 5.5 in distilled water (1:1, w/v); humidity – 17.5%; microbial activity measured by TT C method – 25 mg TPF/g d.w.; TPH – 32 g/kg d.w.; PAHs – 7.8 mg/kg d.w.
Screening of bacteria-producing biosurfactants and their identification are described by Płaza et al. [28, 30]. Evidence of biosurfactant production by Ralstonia picketti SRS and Alcaligenes piechaudii SRS was demonstrated by both microbial and biochemical characterization, and further characterization is planned. Both isolates showed the type of pigmentation on CTAB medium indicated rhamnolipid production [31]. The percentage of 3-hydroxy numbered fatty acids has been correlated with biosurfactant activity [32].