Molecular identification of biosurfactant-producing bacteria obtained from oil-polluted soil samples in Abakaliki, Ebonyi State, Nigeria

Several human activities have led to environmental pollution with crude oil and other related hydrocarbons. There are various technologies of remediating oil-polluted environments, but the use of biological agents such as biosurfactants are widely practiced, and are generally considered as safe and eco-friendly. This study aimed at isolating and identifying biosurfactant-producing bacteria obtained from oil polluted soil samples in Abakaliki, Ebonyi State, Nigeria using molecular techniques. Six waste oil-contaminated soil samples were collected from mechanic and generator repair workshops, and were analyzed using standard microbiological methods. Nine bacterial isolates were obtained from the waste oil-contaminated soil samples, and were suspected to be Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus. Molecular identification of the biosurfactant-producing isolates was also carried out using PCR and the genes responsible for biosurfactant production targeted. Oil spreading technique was used to detect the oil displacement activity (ODA) of the isolates. The emulsification index (E24) was calculated and the ability of the extracted biosurfactant to emulsify the hydrocarbons was determined. Pseudomonas aeruginosa had the highest ODA of 28.1 cm while Staphylococcus aureus had the least ODA of 5 cm. Pseudomonas aeruginosa showed E24 of 70.1%, Bacillus subtilis 57.1% while S. aureus showed 32.5%. Hence, Pseudomonas and Bacillus species have good potentials for biosurfactant production, and can be harnessed and utilized in the cleanup of oil polluted soil.