Insight into Interaction among Soil Microbial Community, Soil Metabolomics and Enzyme Activity after Long-Term PAH Stress

The problem of soil polycyclic aromatic hydrocarbon (PAH) pollution in coking plant sites has been widely studied in recent years, but there is a lack of research on the correlation between soil microorganisms, soil metabolomics, and soil properties. Thus, in this study, the long-term impact of coke combustion on soil microbial community structure, enzyme activities, and metabolic pathways within a former coking plant site was investigated. Soil samples were collected from both the coking production area (CA group) and office area (OLA group), approximately 0 to 20 cm in depth. Compared with OLA group, elevated levels of 16 PAHs in the list of USA EPA were detected by gas chromatography-mass spectrometry in the CA group. Several dominant microorganisms, such as Altererythrobacter, Lysobacter, and Sulfurifustis, were identified by 16 s ribosomal DNA sequencing in the CA group. The fatty acid biosynthesis pathway exhibited specific inhibition, while the phenylalanine metabolic pathway was promoted in response to PAH stress. Long-term PAH exposure led to the inhibition of soil urease activity. The co-occurrence network of microorganisms revealed intricate patterns of co-metabolism and co-adaptation within complex bacterial communities, facilitating their adaptation to and decomposition of soil-borne PAHs. This research could provide valuable insights into the community characteristics and metabolic mechanisms of microorganisms inhabiting PAH-polluted soil within coking plant sites. The findings enhance our understanding of the indigenous soil microbiome and its intricate network dynamics under the persistent stress of PAHs, contributing to a more comprehensive knowledge of soil ecosystems in such environments.