Molecular detection of hydrocarbon degrading bacteria from petrochemical polluted soil

Abstract

Petroleum hydrocarbon pollution remains a major environmental concern, particularly in petroleum-impacted soils in Nigeria. Indigenous bacteria capable of utilizing crude oil offer a sustainable approach to bioremediation. This study investigated hydrocarbon-associated bacteria isolated from petrochemical polluted soil using classical microbiological screening, 16S rRNA gene analysis and GC-MS based degradation assessment. Enrichment and biochemical testing suggested the presence of hydrocarbon-utilizing organisms. PCR amplification of the 16S rRNA gene produced ̴ 1500bp fragments, and BLAST analysis showed 96% and 97% similarity to Pseudomonas and Klebsiella species respectively, indicating affiliation to these genera rather than confirmed species identity. GC-MS analysis of crude oil and before and after 5 weeks of incubation with the isolates showed a marked reduction in hydrocarbon peaks, demonstrating measurable biodegradation activity. It shows that Pseudomonas affiliated organism exhibited the highest degradation efficiency, achieving approximately 90% reduction in total petroleum hydrocarbon (TPHs). This isolate showed strong degradation of short and medium chain alkanes (C ₁₁ - C ₂₀), including complete removal of fractions such as C ₁₆, C ₁₇, C ₂₀, and C ₂₄. However long chain hydrocarbons above C ₂₄ were less affected. The mixed consortium achieved 82% degradation suggesting moderate synergistic interactions, whereas the Klebsiella affiliated isolate showed the lowest activity with 47% TPH reduction. Overall, the findings demonstrate the superior biodegradation performance of the Pseudomonas species and highlight the importance of microbial selection when developing effective bioremediation strategies. The study underscores the relevance of combining molecular profiling with functional GC-MS validation to identify promising hydrocarbon degrading bacteria for remediation of petrochemical polluted soils.