Petroleum-contaminated soils provide an ideal environment for hydrocarbon-degrading bacteria, necessitating the study of their microbial ecology and community changes. This research compared diesel-impacted power plant soil (PPS) from the University of Calabar with pristine soil (CSS) as a control, the samples (50 g) were randomly collected from depths of 0–15 cm, 15–30 cm, and 30–45 cm. Physicochemical and metagenomic analyses were conducted. Taxonomic profiling with functional gene analyses via COG and PRK frameworks performed. PPS displayed higher concentrations of organic carbon (7.02%), total petroleum hydrocarbons (8500 mg/kg), nitrogen (0.51%), phosphorus (3.65 g/kg), lead (175 mg/kg), iron (2619 mg/kg), and copper (196.55 mg/kg) than CSS. Conversely, CSS had higher pH, temperature, conductivity, and moisture content. Bacterial abundance was slightly higher in CSS (89.24%) than in PPS (87.47%), with distinct dominant microbial taxa between samples. Functional analysis identified COG Class I (lipid transport and metabolism) as the most abundant in PPS (32.37%), linked to the predominant hydrocarbon-degrading bacterium Bacillus amyloliquefaciens (26.24%), absent in CSS. In contrast, CSS had COG Class O (posttranslational modification) as the highest (94%). These results demonstrate that petroleum pollution promotes the growth of hydrocarbon-degrading bacteria, underscoring the ecological impacts of contamination on soil microbial communities.
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