scholarly journals Effective Removal of Alkanes and Polycyclic Aromatic Hydrocarbons by Bacteria from Soil Chronically Exposed to Crude Petroleum Oil

Author(s):  
Eman Afkar ◽  
Aly M. Hafez ◽  
Rashid I.H. Ibrahim ◽  
Munirah Aldayel

Abstract In this study, two bacterial strains isolated from an oil-contaminated soil, designated as AramcoS2 and AramcoS4 were able to degrade crude oil, long-chain n-alkanes of C10 to C20; (n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane n-nonadecane, and n-eicosane) and polycyclic aromatic hydrocarbons (PAHs) including biphenyl, naphthalene, and anthracene. Gas chromatography-mass spectrometry (GC-MS) technique was conducted to analyze and identify the crude oil residues after biodegradation. AramcoS2 and AramcoS4 were able to reduce the concentration of long-chain n-alkanes of C10-C20 efficiently on average by 77% of the original concentration. Both isolates could also degrade PAHs on average by 67% of the original concentration within 7 and 14 days of incubation at 30ºC, pH=6.8±0.2. The 16S rRNA gene sequences of AramcoS2 and S4 classified these isolates as Actinobacteria; well-known alkanes and PAHs degraders. The nucleotide sequences of AramcoS2 and AramcoS4 were submitted to the GenBank database under the accession numbers MN142506 and MN142551, respectively. Both isolates can be used to restore the environments contaminated with crude oil components. They should be of great practical significance both in bioremediation of soil contaminated with crude oil and bio-treatment of oil spills on surface water.

2018 ◽  
Vol 20 (3) ◽  
pp. 465-470

<p>In this study, the potential use of Azolla filiculoides Lam. for the bioremediative solution to polycyclic aromatic hydrocarbon (PAH) pollution due to crude oil spills in freshwater was investigated. The plants were grown in nitrogen-free Hoagland nutrient solution media containing 0.05%, 0.1%, 0.2%, 0.3%, 0.4% and 0.5% crude oil by volume for 15 days under greenhouse conditions. Relative growth rates of A. filiculoides decreased in the presence of crude oil in a concentration-dependent manner. The probable influence of A. filiculoides on the biodegradation of polycyclic aromatic hydrocarbons was measured by using synchronous UV fluorescence spectroscopy. GC-MS analysis were also carried out to elucidate the behavior of the oil in experimental and control samples. Although 1-2 rings PAHs have not been encountered in control or plant samples, the measured intensity for 3-4 ring PAHs in plant samples was remarkably lower in comparison to the control. Furthermore, these results demonstrated that the predominant efficacy of the A. filiculoides was for 3-4 ring PAHs at the range 0.05 to 0.2% crude oil concentrations. It could be concluded that the bioremediative potential of A. filiculoides for the removal of polycyclic aromatic hydrocarbons strongly depends on the amount of oil in the contaminated water resource. In other words, A. filiculoides could be used more effectively after the removal of excess crude oil in the spilled freshwater areas.</p>


2013 ◽  
Vol 79 (8) ◽  
pp. 2692-2702 ◽  
Author(s):  
Khajamohiddin Syed ◽  
Aleksey Porollo ◽  
Ying Wai Lam ◽  
Paul E. Grimmett ◽  
Jagjit S. Yadav

ABSTRACTCytochrome P450 monooxygenases (P450s) are known to oxidize hydrocarbons, albeit with limited substrate specificity across classes of these compounds. Here we report a P450 monooxygenase (CYP63A2) from the model ligninolytic white rot fungusPhanerochaete chrysosporiumthat was found to possess a broad oxidizing capability toward structurally diverse hydrocarbons belonging to mutagenic/carcinogenic fused-ring higher-molecular-weight polycyclic aromatic hydrocarbons (HMW-PAHs), endocrine-disrupting long-chain alkylphenols (APs), and crude oil aliphatic hydrocarbonn-alkanes. A homology-based three-dimensional (3D) model revealed the presence of an extraordinarily large active-site cavity in CYP63A2 compared to the mammalian PAH-oxidizing (CYP3A4, CYP1A2, and CYP1B1) and bacterial aliphatic-hydrocarbon-oxidizing (CYP101D and CYP102A1) P450s. This structural feature in conjunction with ligand docking simulations suggested potential versatility of the enzyme. Experimental characterization using recombinantly expressed CYP63A2 revealed its ability to oxidize HMW-PAHs of various ring sizes, including 4 rings (pyrene and fluoranthene), 5 rings [benzo(a)pyrene], and 6 rings [benzo(ghi)perylene], with the highest enzymatic activity being toward the 5-ring PAH followed by the 4-ring and 6-ring PAHs, in that order. Recombinant CYP63A2 activity yielded monohydroxylated PAH metabolites. The enzyme was found to also act as an alkane ω-hydroxylase that oxidizedn-alkanes with various chain lengths (C9to C12and C15to C19), as well as alkyl side chains (C3to C9) in alkylphenols (APs). CYP63A2 showed preferential oxidation of long-chain APs and alkanes. To our knowledge, this is the first P450 identified from any of the biological kingdoms that possesses such broad substrate specificity toward structurally diverse xenobiotics (PAHs, APs, and alkanes), making it a potent enzyme biocatalyst candidate to handle mixed pollution (e.g., crude oil spills).


Author(s):  
Christopher Onyemaechi Ezike ◽  
Felix Okaliwe Echor

One hundred and twenty (120) fingerlings of Clarias gariepinus (mean weight: 0.96 &plusmn; 0.1g) were randomly exposed to 4 experimental treatments of petroleum, based on LC50 values (6.4mg/L of crude oil, 8.7mg/L of petrol, 8.0mg/L of kerosene and 7.8mg/L of diesel oil) and replicated thrice, to determine polycyclic aromatic hydrocarbons (PAH) in exposed fish for 96 h. There was no significant difference (P &gt; 0.05) in total (PAHs) between crude oil (97.1 ng/uL) and diesel (97.2 ng/uL) exposed fish and also between petrol (53.2 ng/uL) and kerosene (49.6 ng/uL) exposed fish, but there was a significant difference (P &lt; 0.05) in PAH levels of the crude oil/diesel exposed -groups of fish compared to petrol/kerosene exposed -groups of fish (97.1/97.2 and 53.2/49.6 ng/uL). Naphthalene correlated positively to benzo a anthracene (r=0.672, (P &lt; 0.05), benzo b fluoranthene (r=0.681, P &lt; 0.05) and chrysene (r=0.615, P &lt; 0.05) but did not correlate to fluorene. Benzo a anthracene correlated positively to benzo a pyrene (r=0.578, P &lt; 0.05), phenathrene (r=0.685, P &lt; 0.05) but did not correlate to acenaphthene. Fluorene correlated positively to benzo a pyrene (r=0.695, P &lt; 0.05) but did not correlate to chrysene. Chrysene correlated positively to dibenzo a,h, pyrene (r=0.658, P &lt; 0.05) to phenathrene and benzo b fluoranthene (r=0.659, P&lt; 0.05). Indeno 123 cd- pyrene and fluranthene however did not correlate to other PAHs except naphthanene, acenaphthene and acenaphthylene. The level of PAH in fish may translate to the toxicity effect since crude oil and diesel with lower LC50 (6.4 and 7.8 mg/L)&nbsp;&nbsp; deposited greater PAH than kerosene and petrol with higher LC50 (8.7 and 8.0 mg/L) in fingerlings of C. gariepinus. High risk to cancer disorders may occur in exposed fish to petroleum with high incidence of fluorene , anthracene, pyrene and benz a anthracene which correlated positively to benzo a pyrene which provide some basis for predicting impact of oil spills on fingerling population.


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