Molecular characterization of a polycyclic aromatic hydrocarbons (PAHs) degrader, Burkholderia contaminans strain P14, isolated from aged oil-contaminated soil in Kuwait

Abstract

Soil contamination by polycyclic aromatic hydrocarbons (PAHs) is a major environmental issue affecting soil quality and health. Bioremediation is an efficient approach to decontaminate these pollutants while posing the lowest risk to the environment. In this study, the physiochemical properties of oil-contaminated soils in Kuwait were investigated, selective screening and genetic identification of PAH degraders were performed, and the PAHs degradation pathway was predicted. High concentration of PAHs was detected in the soil samples, in particular for pyrene, phenanthrene, and fluorine. In total, 21 strains belonging to the genera Pseudomonas (9), Burkholderia (6), Bacillus (2), Bordetella (1), Microbacterium (1), Micrococcus (1), and Kocuria (1) showed ability to degrade PAHs. Burkholderia sp. P14 demonstrated a stable growth rate (5 to 8 days) in the presence of phenanthrene and fluorene. The genome sequence of the Burkholderia contaminans P14 strain comprises 80 genes involved in the degradation of the benzoate, and PAHs. The genes encoding for PAHs degradation were clustered into four distinct groups, including pcaHG, pcaB, pcaIJ, and pcaKFR. KEGG analysis suggested that PAHs were degraded in P14 via the protocatechuate and catechol branches of the β-ketoadipate protocatechuate degradation pathway. The genomic island regions in P14 differed from those in the reference genome of B. contaminans M14, indicating the novelty and genomic recombination of the strain. In conclusion, B. contaminans P14 strain has great potential to be used as bio-degrader for the restoration of oil-contaminated soils.