_applied sciences_  
_Isolation and Characterization of Oil-Degrading_ Enterobacter_  
sp. from Naturally Hydrocarbon-Contaminated Soils and Their Potential Use against the Bioremediation of Crude Oil  
[PERSON] 1,2, [PERSON] 1,2,  
reason for the decline in soil productivity and crop production [5; 6; 7]. Currently, the major toxic contaminants are pesticide residues, petrol-related products, heavy metals, and polycyclic-aromatic hydrocarbons, and pollution with these contaminates poses severe hazards to the environment and human health [1; 8; 9]. The contamination of soils with crude oil and its derivatives is a significant environmental issue worldwide [10; 11; 12]. Hydrocarbons make their way into the soil during oil extraction, storage, and distribution, refining, and processing; in addition, leaks and discharge of petroleum hydrocarbons sometimes occur as a consequence of blow-out accidents during oil field growth, oil pipelines and storage tank leakages, oil vessels and vessel leakage accidents, the well waxing of oil, and refinery and petroleum chemical manufacturing equipment [13; 14]. With the continuous increase in demand for petroleum and oil products, the contamination of soil with petroleum hydrocarbons has also increased exponentially [15]. Thus, attention is required to be paid to marine and terrestrial ecosystems that are being degraded due to contamination with crude oil [16]. In this regard, numerous physico-chemical techniques can be utilized for the remediation of crude oil and other polycyclic-aromatic hydrocarbon-contaminated soils [17]. The chemical remediation of soil includes neutralization, oxidation reduction, and solvent extraction [18; 19], while the physical remediation of soil includes incineration, soil washing, and vacuum extraction [15; 20]. Although these methods to remediate polycyclic-aromatic hydrocarbons are effective, these approaches are generally neither cost-effective nor environmentally friendly [10; 21]. Furthermore, in situ remediation technologies--i.e., chemical remediation and physical remediation--increase the mobility of contaminants in the soil and may contaminate the underground water [22; 23]. Oil bioremediation is accepted internationally as a cost-effective and environmentally sustainable solution [13; 24]. bioremediation involves two separate processes: bio-stimulation and bio-augmentation (inoculation, seeding) [25]. Bio-stimulation is based on current (native) microbes that can be improved by the careful control of their activities [26]. To improve the remediation of crude oil by microbes in crude oil-contaminated soil, the optimal management of nitrogen and phosphorous fertilizers is important for microbial survival [27]. Bio-augmentation requires the inoculation into the contaminated environment of exogenous microorganisms [28]. In other terms, this strategy ensures that more active microbial strains are introduced to the crude oil-polluted sites [29]. Biomerediation is also characterized as \"self-cleaning\" and relies on oil remediation by the already existing microbes in contaminated soil without any precise management [10; 30]. Recent studies have established more than 79 genera of bacteria that are able to degrade petroleum hydrocarbons [31], and indeed, several experiments have shown that there are a significant number of hydrocarbon-remediating bacteria in oil-rich areas such as oil spills and oil reservoirs, and that their frequency and amount are directly linked to the forms of petroleum hydrocarbons and the environmental factors affecting them [14; 32]. From the previous literature, it was revealed that various microbial species such as _Achromobacter xylos oxidans_[33], _Aeribacillus pallidus_[34], _Geobacillus thermodentirtian_[35], _Gordonia sliwensis_[36], and _Pseudomonas aeruginosa_[37] play vital roles in the degradation/remediation of petroleum hydrocarbons [38]. Recently, very low amounts of crude oil--i.e., 1-6%--have been used in most bacterial remediation studies [14; 39].