The need to know the level of contamination of radioactive elements, especially Microbial populations are crucial for the environment, providing vital ecosystem services such as biogeochemical cycling, decomposition, and degradation, which essential vital for the survival of all life forms on Earth. This study investigated the heterotrophic bacterial and fungal isolates in crude oil polluted sediment from the Eniong River using standard conventional analytical and culture-dependent techniques. The mean total heterotrophic bacterial (THBC) and mean total fungal counts (THFC) in sediment samples from the three stations of Eniong river sediment was 9.3 x 104 CFU/g and 2.4 x 104 CFU/g, respectively. The heterotrophic bacterial count was highest in location A (upstream) and lowest in location C (downstream) while the lowest fungal count was obtained in location B (midstream) and highest in location C (downstream). The results revealed diverse bacterial and fungal assemblages and ecosystem's richness in microbial diversity. Twelve (12) bacterial species from the genera Staphylococcus, Salmonella, Shigella, Escherichia, Bacillus, Klebsiella, Micrococcus, Aeromonas and Pseudomonas were isolated. The eight (8) fungal species belonging to genera Aspergillus, Penicillium, Rhizopus, Geothrichium, Candida and Mucor were obtained. Bacillus cereus was the most prevalent bacterial isolate, accounting for 16%, while the least isolated bacteria were Aeromonas sp. and Salmonella sp. (4%). The most isolated fungi was A. niger (31.8%), while A. fumigatus (13.6%) was the least occurring fungal isolates. The findings clearly demonstrated that the sediment of the Eniong River provided a unique ecological niche that supports a variety of microorganisms.

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