Culture-Dependent Characterization of Hydrocarbon Utilizing Bacteria and Fungi from an Artisanal Crude Oil Refining Site

Abstract

Crude oil refining is a global insert responsible for the production of a wide array of petroleum based products crucial for various sectors including energy, transportation, and manufacturing. However, the artisanal form of crude oil refining, often characterized by its small scale and limited technological infrastructure, has emerged as a major environmental concern in several regions around the world. Illegal refining of crude oil has led to oil spillages which in turn lead to a disruption of the microbial population of the soil. Hence, the aim of this study was to isolate and characterize the heterotrophic and hydrocarbon utilizing bacteria and fungi from an artisanal crude oil refining site. A total of thirty six (36) soil samples were collected from three (3) artisanal crude oil refining sites at iwofe, ogbogoro and ibaa community all in Rivers State, Nigeria. The samples were collected using soil auger and subjected to standard microbiological procedures such as culturing, isolation and identification. The results revealed significantly elevated levels of heterotrophic and hydrocarbon utilizing bacteria and fungi in the soil samples, with notable variations (p≤0.05) across the different artisanal crude oil refining sites. Total Heterotrophic Bacteria (THB) counts ranged from 3.75x105CFU/g in Iwofe to 2.70x105CFU/g in Ibaa, Total heterotrophic Fungal (THF) counts ranged from 2.80x104CFU/g recorded in Ogbogoro to 1.45x104CFU/g recorded in Iwofe, Hydrocarbon Utilizing Bacteria (HUB) counts ranged from 2.25x103CFU/g in Ibaa to 1.30x103CFU/g in Iwofe and Hydrocarbon Utilizing Fungi (HUF) counts ranged from 2.50x102CFU/g recorded in Ogbogoro to 1.40x102CFU/g recorded in Ibaa community with significant differences (p≤0.05). Bacteria isolated and characterized from the soil include Enterobacter, Pseudomonas putida, Serratia and Bacillus amyloliquefaciens while fungi include Fusarium, Aspergillus, Penicillium and Mucor. The microorganisms identified in this study have been reported to play key roles in the utilization of crude oil. Pseudomonas and Bacillus were the most dominant bacterial isolates and their dominance could imply that the soil could support the growth of crops. Thus, while they utilize the hydrocarbons, they also serve as plant-growth promoting microorganisms. Although some of the microorganisms in the present study have been reported to promote the growth of plant, the dumping of crude oil products legal or illegal should be minimized to avoid the extinction of plant-promoting microorganisms.