Remediation capacity of drought-tolerant plants and bacteria in petroleum hydrocarbon-contaminated soil in Iran.

• Drought tolerant plant species had better phytoremediation potential in contaminated soil. • Plant-bacteria interaction enhanced bioremediation potential in TPHs contaminated soils. • Eucalyptus showed better bioremediation potential among experimental plants. • Application of fertilizer improved bioremediation efficiency of plant and bacteria. Ex-Situ bioremediation techniques such as synthetic surfactants and bioreactors to detoxify petroleum contaminated soil are costly and have harmful environmental consequences. This study was conducted to evaluate the intrinsic bioremediation potential of native, compatible and drought-tolerant plants and bacteria for removing total petroleum hydrocarbons (TPHs) from the soil. Furthermore, the potential of fertilizer for increasing the bioremediation capacity of these organisms was assessed. The study was performed as a completely randomized factorial design experiment with four replications. The plant treatments were Opuntia ficus-indica (P1), Eucalyptus camaldulensis, (P2) and Nerium oleander (P3). The bacteria treatments were Bacillus pumilus (B1), Pseudomonas putida (B2), and the combined use of these two bacteria and a fertilizer recommendation (B1B2F). The control treatment included only contaminated soil without plant, bacteria, and fertilizer. The results indicated that plant and bacteria treatments enhanced the decomposition of soil TPHs significantly (α=0.01). P2B1B2F was found to be the most efficient treatment, removing 77.30% of soil TPHs. Eucalyptus camaldulensis cultivation along with P. putida (P2B2) reduced TPHs by 69.60%. P. putida was more efficient than B. pumilus in reducing TPHs. Interactions between plants and bacteria increased root and total dry weight of plants significantly (α=0.01). Application of bacteria and the fertilizer recommendation increased the decomposition rate of TPHs and improved phytoremediation efficiency. Rehabilitation by Eucalyptus camaldulensis with bio-fertilization of soil using P. putida and chemical fertilizers is recommended for the bioremediation of soil contaminated with TPHs. [ABSTRACT FROM AUTHOR]