BIONATURE

Hydrocarbon contamination alters soil physicochemical properties and selectively shapes microbial community structure by favoring hydrocarbon-utilising bacteria (HUB) and stress-tolerant taxa, while potentially suppressing sensitive heterotrophic and fungal populations. This study assessed culturable bacterial and fungal communities in hydrocarbon-impacted soils from three oil-producing communities (Otuan, Imiringi, and Obuna) in Bayelsa State, Nigeria. Composite soil samples were collected at 0–10 cm and 10–30 cm depths and analyzed using standard culture-based methods. Total heterotrophic bacterial counts (THBC) were higher in surface soils, ranging from 51.0 ± 2.65 to 69.0 ± 3.00 × 10⁴ CFU g⁻¹, compared with subsurface values of 23.3 ± 2.52 to 45.0 ± 3.00 × 10⁴ CFU g⁻¹, with significant spatial variation (p < 0.001). Hydrocarbon-utilizing bacteria ranged from 18.3 ± 2.52 to 20.3 ± 2.52 × 10⁴ CFU g⁻¹ at 0–10 cm and 11.0 ± 2.00 to 17.0 ± 2.00 × 10⁴ CFU g⁻¹ at 10–30 cm. Total fungal counts ranged from 15.3 ± 2.52 to 21.0 ± 2.65 × 10⁴ CFU g⁻¹ at 0–10 cm and 10.0 ± 2.00 to 13.0 ± 2.00 × 10⁴ CFU g⁻¹ at 10–30 cm. Dominant isolates included Pseudomonas aeruginosa, Bacillus cereus, Aspergillus niger, and Penicillium sp., indicating adaptation to petroleum contamination and bioremediation potential. However, the study was limited by culture-dependent methods, absence of physicochemical data, and small sample size. Future studies should integrate molecular sequencing and broader environmental assessment.