Molecular Characterization of Hydrocarbon-utilizing Rhizobacteria from Hydrocarbon-impacted Mangrove Soil in Ogoni Land, Nigeria

Aim: This study investigated the molecular characterization of hydrocarbon-utilizing rhizobacteria isolates from hydrocarbon-impacted mangrove soil from K-Dere Gokana and Gio Tai, Ogoni land, Nigeria.

Study Design: Cross-sectional study.

Place and Duration of Study: K-Dere Gokana and Gio Tai, Ogoni land, Nigeria, between June 2019 and June 2020.

Methodology: Hydrocarbon-utilizing bacteria were isolated from the rhizosphere of hydrocarbon-impacted mangrove soil. Baseline physicochemical and microbiological characteristics of the rhizosphere soil from the contaminated sites were determined. Hydrocarbon utilization was determined turbidometrically using a spectrophotometer and by growth on Bushnell, Haas agar supplemented with 1% crude oil.

Results: Analysis of the rhizosphere soil revealed that the site was contaminated with crude oil with a TPH value of 547.62±40.15 mg/kg. Based on phylogenetic analysis of these 16S rRNA genes the isolates were classified as Bacillus thuringiensis SA2-1; Bacillus velezensis SA11-2; Morganella morganii SA4-3; Serratia ureilytica SB1-4; Serratia marcescens SB5-5 and Serratia nematodiphila SB16-6. The sequences have been deposited under the accession numbers MN631244.1-MN631249.1. These bacteria all demonstrated efficient hydrocarbon utilization in Bushnell medium with 1% crude as the sole carbon source. These bacteria are well documented putative hydrocarbon utilizers.

Conclusion: This study has demonstrated that hydrocarbon utilization from different genera was associated with the rhizosphere of hydrocarbon-impacted mangroves in Gio and K-Dere.