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.