Abstract

Hydrocarbon contamination poses a significant threat to aquatic ecosystems, necessitating the identification of indigenous microorganisms capable of degrading petroleum hydrocarbons. This study investigated the diversity and phylogenetic relationships of hydrocarbonoclastic bacteria isolated from Sombreiro River that is contaminated by hydrocarbons. Bacterial isolates were harvested and cultured following standard microbiological procedures. Isolates demonstrating hydrocarbon-utilizing potential were subsequently analyzed using the polymerase chain reaction (PCR) technique. Their 16S rRNA genes were sequenced and compared with reference sequences available in the National Center for Biotechnology Information (NCBI) database to establish their taxonomic identities and assess their phylogenetic relationships. Phylogenetic analysis revealed the presence of diverse hydrocarbon-degrading bacterial species belonging to the genera Bacillus, Enterobacter, Providencia, Shewanella, and Pseudomonas. The isolates were identified as Bacillus flexus (AE1) (recent name Priestia flexa), Bacillus subtilis (DE2), Enterobacter cloacae (KE2), Providencia startii (IE2), Shewanella algae (OV2 and DE3), Pseudomonas xiamenensis (SE3), and Pseudomonas plecoglossicida (DV6) and their Accession numbers are MT645459.1, OQ726278.1, OR426319.1, MK641351.1, MT549169.1, MN611113.1 and MT498800.1 respectively. The occurrence of multiple hydrocarbonoclastic genera suggests the existence of a microbial consortium capable of synergistic degradation of complex hydrocarbon mixtures. Such microbial diversity enhances the potential for natural attenuation and bioremediation of polluted environments. The study highlights the importance of indigenous hydrocarbon-degrading bacteria from Sombreiro River and provides valuable molecular evidence supporting their application in bioremediation programs. The identification of genetically diverse and environmentally adapted bacterial strains offers promising prospects for the development of efficient, eco-friendly strategies for the remediation of hydrocarbon-contaminated ecosystems and the sustainable management of petroleum pollution.