Petroleum oil contaminants have become severe ecological problems and negatively impact human health. It is, therefore, imperative to identify environmentally friendly approaches to remediate oil-polluted environments. Therefore, bacterial oil degradation stimulated with a nitrogen source under optimum conditions was assessed in this study. Based on the 16S rRNA analysis, strain ODB H32 recovered from oil-based mud of some petroleum drilling sites in the western desert, Egypt, was identified as Enterobacter hormaechei. The metabolic fingerprint of E. hormaechei, achieved using BIOLOG GEN III, revealed that the strain could utilize diverse carbon and chemical sources. Also, E. hormaechei could biodegrade 0.6% of oil under optimized pH (7.0) and temperature (30 °C) conditions. Analyzing different nitrogen stimulants revealed that peptone ˃ yeast extract ˃ ammonium nitrate ˃ urea enhanced the growth of E. hormaechei on mineral salts medium (MSM). Analysis by capillary gas chromatography revealed maximum (70.7%) degradation of peptone by E. hormaechei, indicating that peptone was a good biostimulant for oil degradation. These findings recommend using biostimulated E. hormaechei as an eco-friendly approach for remediating oil-polluted environments, under optimized conditions, especially in arid regions like the western desert of Egypt.

The main aim of this study is to isolate, screen and identify the most potent oil degrading bacteria (ODB) isolated from oil base mud (OBM) waste resulted from group of selected oil and gas drilling and exploration wells. Another aim is to determine the metabolic fingerprint of the most potent ODB. To achieve these aims, eleven samples from the waste of oily base mud were collected from different drilling sites at western desert. Total bacterial counts at 22 oC and 30 oC were determined for giving a full picture about the presence of natural bacterial flora in the collected samples. Moreover, ODB were determined on oil agar media containing 0.1% oil (V/V) using spread plate method. The results showed that, the average of total bacterial counts at 22 oC and 30 oC were 1.4x104 and 1.6x104 CFU/g, respectively. Moreover, the oil degrading bacteria (ODB) counts were fluctuated between 1.0×102 and 6.1x103 CFU/g in all collected samples. After six screening steps, the most potent oil degrading bacteria were identified using BIOLOG as follows Enterobacter hormaechei, Enterobacter cloacae and Bacillus subtilis. The only difference in the metabolic fingerprints view between two bacterial strains that, Enterobacter hormaechei (H17) are able to utilize D-serine while and Enterobacter cloacae (H32) not. It can be concluded that, metabolic fingerprints of the most potent oil degrading bacteria provide full information