Global Geographic Patterns of Soil Microbial Degradation Potential for Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are toxic and persistent pollutants that are widely distributed in the environment. PAHs are toxic to microorganisms and pose ecological risks. Bacteria encode enzymes for PAH degradation through specific genes, thereby mitigating PAH pollution. However, due to PAHs' complexity, information on the global degradation potential, diversity, and associated risks of PAH-degrading microbes in soils is lacking. In this study, we analyzed 121 PAH-degrading genes and selected 33 as marker genes to predict the degradation potential within the soil microbiome. By constructing a Hidden Markov Model, we identified 4990 species carrying PAH-degrading genes in 40,039 soil metagenomic assembly genomes, with Burkholderiaceae and Stellaceae emerging as high-potential degraders. We demonstrated that the candidate PAH degraders predominantly emerged in artificial soil and farmland, with significantly fewer present in extreme environments, driven by factors such as average annual rainfall, organic carbon, and human modification of terrestrial systems. Furthermore, we comprehensively quantified the potential risks of each potential host in future practical applications using three indicators (antibiotic resistance genes, virulence factors, and pathogenic bacteria). We found that the degrader Stellaceae has significant application prospects. Our research will help determine the biosynthetic potential of PAH-degrading enzymes globally and further identify potential PAH-degrading bacteria at lower risk.