Bioelimination of phenanthrene using degrading bacteria isolated from petroleum soil: safe approach

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Polyaromatic hydrocarbon contamination is considered as serious pollution resulted from industrial activities. Physical or chemical methods used for remediation of hydrocarbons might cause the transfer of the remediated compounds from the polluted sites into other clean locations. Our study is concerned by the bioremediation of phenanthrene, using microbial degraders that will eventually, result in the release of non-toxic structures, as end products. Successfully, three bacterial isolates; Enterobacter cloacae, Bacillus sp. and Bacillus thuringiensis with accession numbers; MK559694, MK561601 and MK559693, respectively, showed higher phenanthrene biodegradation ability. The examined conditions indicated that the isolates were active in a wide range of temperatures, pH and hydrocarbon concentrations. The gas chromatography-mass spectrum analysis of the formed by-products showed the existence of intermediate structures with varied carbon values, ranged from C 4 H 8 O 2 to C 12 H 22 O 11 . However, these by-products did not show cytotoxic effect against Vero cell lines, compared with the tested undegraded phenanthrene. The obtained results revealed that these bacterial isolates can be used as potent phenanthrene degraders with safe and non-toxic end products, which allow the treated water to be used for non-potable water applications.