Exploring Novel Microorganisms for PAH Degradation in Egyptian Soil: A Bioremediation Strategy for Soil Detoxification.

Introduction: Polycyclic aromatic hydrocarbons (PAHs) are toxic petroleum byproducts in soil, exhibiting significant genotoxic properties. Microorganisms residing in contaminated soils serve as effective detoxifying agents. Among various strategies, bioremediation is an efficient biological method for detoxifying PAHs.

Method: Hundreds of soil samples were collected from the Gulf of Suez, Egypt. The isolation process utilized an enrichment culture system with phenol naphthalene (PN) (10 mg/mL) as the primary carbon source. HPLC analysis was applied to confirm PN degradation. Consequently, the bacterial strain was characterized morphologically, biochemically, and through partial sequencing of its 16S rRNA gene. Subsequently, its plasmid was purified to transfer its phenotype to Escherichia coli. Finally, a bioremediation approach was conducted to test its PAH degradation.

Results: HPLC analysis was performed to confirm PN degradation by the isolated strain. The isolated strain was identified as Lysinibacillus species AAS1 (OR044755.1) with 98.43% sequence similarity to the Lysinibacillus genus. Subsequently, E. coli transformants with the isolated plasmid were grown in the presence of PN as the primary carbon source. Finally, the bioremediation assay of the isolated strain exhibited a high efficiency in detoxifying PN.

Discussion: The novel identified Lysinibacillus species AAS1 (OR044755.1) shows promise for PAHs detoxification, which may lead to the exploration of a biological agent for the remediation of water and soil contaminated with PAHs.

Conclusion: A novel bacterial strain bearing a plasmid that can degrade PN was isolated from Egyptian petroleum waste-contaminated soil. It paved the way for further studies to isolate the whole gene(s) responsible for such degradation.