Sphingomonas Relies on Chemotaxis to Degrade Polycyclic Aromatic Hydrocarbons and Maintain Dominance in Coking Sites

Polycyclic aromatic hydrocarbons (PAHs) are organic pollutants widely present in industrial sites. Microbial degradation is an effective method of removing PAHs. The identification of microorganisms that have important ecological functions at the site is of great significance for PAH removal. We collected soil samples at three depths in the range of 0-100 cm at 70-day intervals at the coking site and explored the degradation of PAHs. We combined molecular ecology networking, metagenomics, and genome assembly to search for microorganisms that persist, dominate, and affect the microbial community construction in the degradation process and analyzed their adaptation strategies. The results showed that 15.78 mg/kg of PAHs naturally decayed, and 13.33 mg/kg of PAHs migrated from 30-100 cm to 0-30 cm in the soil. Sphingomonas, which occupied a niche advantage, was both the core and keystone microorganism, and its spatial distribution pattern and temporal change dynamics were consistent with those of PAHs. We assembled the genome of Sphingomonas sp., revealing its multiple potential for degrading PAHs and other pollutants. Additionally, flagellar assembly and bacterial chemotaxis genes ranked high in the assembled genome of Sphingomonas sp., which might help it obtain a competitive advantage in the soil. The findings underscored the strategy of Sphingomonas to maintain dominance, enriched the understanding of PAH-degrading microorganisms in site soil, and provided references for the remediation of PAHs.

Automated summary

In this study, soil samples were collected at a coking site to investigate the degradation of polycyclic aromatic hydrocarbons (PAHs) using a combination of molecular ecology networking, metagenomics, and genome assembly. The dominant and persistent microbe, Sphingomonas, was identified and its adaptation strategies and genomic features were analyzed. The study revealed that Sphingomonas plays a crucial role in the degradation of PAHs and demonstrated its competitive advantage in the soil environment.