Oil-contaminated Sites Research Articles

Isolation and Characterization of Biosurfactant Producing Pseudomonas aeruginosa YLA03 and its Diesel Degradation Potentials

This work was aimed at isolating and characterising biosurfactant producing bacteria strain from diesel oil contamination sites. The potential of the strain to degrade diesel oil n-alkanes was further studied. Soil samples were collected from diesel rich areas, and identified strains were grown on minimal media that contained diesel oil as only carbon source. Enrichment culture technique was used to identify bacteria. Seventeen bacteria strains were identified based on their capacity to use diesel oil as carbon source. Other qualitative screening methods were employed to determine the potential to produce biosurfactants. Isolate A03 was the only candidate that shows positive signs for drop collapse, foaming, haemolytic, oil displacement and emulsification tests. The effect of various culture parameters (incubation time, concentration of diesel, nitrogen source, pH and temperature) on biodegradation of diesel was evaluated. Optimum pH was 8.0 at 35° C, while the incubation time at maximum bacteria growth was five (5) days. The favourable diesel oil concentration was 7.5% for the isolate. The isolate has shown degradative ability towards dodecane, Tridecane, tetradecane but was unable to degrade 2, 6, 10-trimethyl- dodecane. It degraded between 10.09% - 45.39% of individual diesel alkanes. The strain has exhibited potential for degrading diesel alkanes and was identified as pseudomonas aeruginosa strain A3 (Accession Number: MZ027605) using the 16S rRNA. Sequencing.

Natural and Technical Phytoremediation of Oil-Contaminated Soil.

Natural and technical phytoremediation approaches were compared for their efficacy in decontaminating oil-polluted soil. We examined 20 oil-contaminated sites of 800 to 12,000 m2 each, with different contamination types (fresh or aged) and levels (4.2-27.4 g/kg). The study was conducted on a field scale in the industrial and adjacent areas of a petroleum refinery. Technical remediation with alfalfa (Medicago sativa L.), ryegrass (Lolium perenne L.), nitrogen fertilizer, and soil agrotechnical treatment was used to clean up 10 sites contaminated by oil hydrocarbons (average concentration, 13.7 g/kg). In technical phytoremediation, the per-year decontamination of soil was as high as 72-90%, whereas in natural phytoremediation (natural attenuation with native vegetation) at 10 other oil-contaminated sites, per-year decontamination was as high as that only after 5 years. Rhizodegradation is supposed as the principal mechanisms of both phytoremediation approaches.

STUDY OF OIL DEGRADATION IN OIL-CONTAMINATED SOIL DURING PURIFICATION USING A BIOLOGICAL PRODUCT

During a scientific study, a laboratory experiment was conducted to investigate the degradation of oil by various microorganisms in a liquid mineral medium containing 2% oil. This experiment was conducted at temperatures of 24ºC and 5ºC for a duration of 10 days. Using infrared spectroscopy (IR spectroscopy), the degree of oil decomposition by each microorganism was determined. Based on these data, four associations of microorganisms were created, which proved to be effective in breaking down oil hydrocarbons. Using gravimetry and IR spectrometry, the degree of oil biodegradation by these microorganism associations was assessed, ranging from 30% to 70%. Based on the data obtained regarding microbial associations, a new bio-preparation was developed, containing the Pseudomonas sp. K3-H strain and two Rhodococcus strains (F2/2-Н4, F2/1-Н4). Subsequently, fieldwork was conducted on the premises of oil waste of the company "TOO Company – Daulet Asia." Over a period of 12 weeks, the population of oil-degrading microorganisms at the oil-contaminated site reached the required level, resulting in an 89.67% reduction in the amount of oil. It is worth noting that the ambient temperature varied from 05 to 39°C during the day and from 0 to 24°C at night during this period. The results of the field studies demonstrated the effectiveness of the developed bio-preparation based on the Rhodococcus erythropolis KZ1, Rhodococcus erythropolis KZ2, and Pseudomonas putida KZ3 strains. Thus, the proposed bioremediation strategy utilizing the developed bio-preparation successfully passed the testing phase at the landfill of "TOO Company - Daulet Asia" in the Kyzylorda region of the Republic of Kazakhstan.

Techniques of Bioremediation using bacteria for the treatment of polycyclic aromatic hydrocarbons: A Review

The term "hydrocarbon" is self-explanatory and refers to solely carbon and hydrogen compounds. Hydrocarbons play an important role in our everyday lives. Hydrocarbons, particularly polycyclic aromatic hydrocarbons, harm biota. The relatively fast introduction of xenobiotic compounds, as well as the enormous movement of natural materials to various environmental compartments, can often overwhelm the self-cleaning capabilities of the recipient ecosystem, resulting in pollution and accumulation of hazardous or even lethal levels. Bacteria capable of hydrocarbon degradation are frequently used in the bioremediation of fuel oil-contaminated sites. Presently, multiple sophisticated methodologies, transcriptomics, proteomics and are effectively utilized for the depiction of hydrocarbons degrading microorganisms. These expertises are highly developed, and its integration with bioinformatics tools makes it even more efficient. Though health science and biological science are the major relevant areas for molecular docking, it has been effectively used to explore the process of bio-degradation in ecological remediation in recent years. This review focuses on the sources, fate of PAHs, human exposure, various computational aspects associated with PAHs, and some approaches of synthetic biology related to pollutant degradation and PAH‑degradation by genetically engineered microorganisms.

Migration behaviour of LNAPL in fractures filled with porous media: Laboratory experiments and numerical simulations

With the increasing requirement of maintaining world energy security and strategic reserves, oil storage and transportation facilities are being built at a large scale. Taking the safe and efficient operation of petroleum storage projects as the goal, a set of experimental apparatus to investigate the migration of contaminants in fractures filled with media was developed to predict and evaluate the environmental risk of oil contaminants leakage. A multiphase numerical flow model based on COMSOL was built based on the laboratory experimental model. Specifically, the migration behaviour of Light Non-aqueous Phase Liquid (LNAPL) through a sand-filled fractured medium was studied by laboratory experiments and numerical simulations. Image and chemical analyses methods were used to monitor and study LNAPL migration behaviour for varying grain sizes of porous medium filling the fractures and varying groundwater table elevations. Laboratory experimental results showed that the LNAPL migration velocity in filled fracture network was significantly faster than that in adjoining porous media during the initial stage of infiltration. The migration velocity increased with the relative permeability of filled sand, which was closely related to the Van Genuchten (VG) model parameters α and n. LNAPL migrated downward with the falling groundwater table and became entrapped with the rising groundwater table, and the amount of entrapment depended on VG model parameters. Hydrogeological parameters were calibrated and LNAPL migration in filled fractured media was predicted using the calibrated numerical model. Simulation results revealed that fracture inclination had an important influence on LNAPL migration in filled fractured media and its migration velocity decreased with a decrease in fracture inclination. These research results can be applied to the control and remediation of oil-contaminated sites in fractured rock settings, such as at underground oil storage tanks and caverns, as well as at underground oil pipelines.

Identification of hydrocarbon-degrading bacterial consortium isolated from the oil-contaminated muddy soil in Hanoi, Vietnam

Bioremediation is a promising approach for treating oil-contaminated environments. The main objective of this study was to isolate bacteria capable of degrading hydrocarbons for application in oily wastewater treatment from oil-contaminated sites in Hanoi, Vietnam. The bacterial consortium studied was obtained from an oil-contaminated muddy soil sample enriched with crude oil mixed with diesel oil as a carbon source. The reconstituted consortium was able to degrade 93% of the oil content after 7 days of testing. A total of five pure bacterial strains were isolated on TSA agar from the complex microbial communities and were selected as potential candidates for oily sludge biodegradation processes. These isolates were identified based on their morphological and biochemical characteristics. By using molecular biology techniques, five hydrocarbons degrading bacteria were investigated and identified as Pseudomonas mendocina strain MD1 (OL687411.1), Pseudomonas hydrolytica strain MD2 (OL771695.1), Brucella intermedia strain MD3 (OL687412.1), Pseudomonas stutzeri strain MD4 (OL687413.1), and Stenotrophomonas nitritireducens strain MD5 (OL687414.1). The morphological and biochemical characterization of these bacteria showed that five of them were Gram-negative, rod-shaped, catalase positive, the ideal pH was neutral, and the optimum growth temperature was 30ºC in a culture medium with a salinity of 0.5%. These strains are capable of producing extracellular enzymes, such as lipase, amylase, cellulase, and protease.

Enhancing biodesulfurization by engineering a synthetic dibenzothiophene mineralization pathway.

A synthetic dibenzothiophene (DBT) mineralization pathway has been engineered in recombinant cells of Pseudomonas azelaica Aramco J strain for its use in biodesulfurization of thiophenic compounds and crude oil. This functional pathway consists of a combination of a recombinant 4S pathway responsible for the conversion of DBT into 2-hydroxybiphenyl (2HBP) and a 2HBP mineralization pathway that is naturally present in the parental P. azelaica Aramco J strain. This novel approach allows overcoming one of the major bottlenecks of the biodesulfurization process, i.e., the feedback inhibitory effect of 2HBP on the 4S pathway enzymes. Resting cells-based biodesulfurization assays using DBT as a sulfur source showed that the 2HBP generated from the 4S pathway is subsequently metabolized by the cell, yielding an increase of 100% in DBT removal with respect to previously optimized Pseudomonas putida biodesulfurizing strains. Moreover, the recombinant P. azelaica Aramco J strain was able to use DBT as a carbon source, representing the best characterized biocatalyst harboring a DBT mineralization pathway and constituting a suitable candidate to develop future bioremediation/bioconversion strategies for oil-contaminated sites.

Screening of Biosurfactant-producing Bacteria from Symbiotic Microbes with Gastropods in the Persian Gulf

Introduction: Biosurfactants or surface-active compounds with amphiphilic molecular structures, including a hydrophilic and a hydrophobic domain, are produced by microorganisms. These compounds increase the biodegradation of hydrocarbons in the environment due to their ability to emulsify hydrocarbon-water mixtures. This study was conducted to isolate and characterize biosurfactant-producing bacteria from the samples of Gastropods. 
 Materials and Methods: The gastropod samples were collected from oil-contaminated sites in the Persian Gulf, Middle East. Biosurfactant-producing strains were isolated from these samples. The biosurfactant production ability was analyzed using Drop Collapse TEST, oil spreading test, emulsification activity test, and BATH test.
 Results: In total, 11 biosurfactant-producing strains were isolated. Two isolates with higher growth rates and biosurfactant production ability were selected for further studies. The best isolates were identified as Halomonas sp. isolate BHA16 and Vibrio alginolyticus isolate BHA 17 based on molecular analysis. Gas chromatography analysis of remaining crude oil confirmed that these strains could degrade to 51.44 % and 67.58% of crude oil, respectively.
 Conclusion: The results of this study indicated the surfactant activity of the bacterial strains isolated from Gastro pods had a good potential for the biodegradation of crude oil and could be used for the cleanup of oil-contaminated marine environments.

Hydrocarbon degradation test among the microbial community in oil-contaminated soil of power generators in Kerbala city, Iraq

The present study was designed to isolate the microbial community from oil-contaminated sites and other non-oil-contaminated sites which served as control samples in Kerbala city. In addition to test the effect of hydrocarbons on the growth of some types of bacteria. Bacterial genera and species were identified based on their growth on nutrient agar and blood agar as well as biochemical tests. According to the high bacterial growth rate on crude oil, 5 bacterial isolates were selected for further study. Growth of some identified bacteria in Minimal salt medium amended with hydrocarbon as the sole carbon source was investigated. Acinetobacter sp., Pseudomonas aeruginosa, Pseudomonas fluorescens, Pantoea sp., Pasteurella pneumonia / haemolytica, Chryseobacterium meningosepticum, Bordetella sp., and Enterobacter cloacae were the dominant phyla among all the soil samples. Although all tested bacteria were able to grow on mineral liquid media, P. aeruginosa had the most capacity for growth in this media. The present study showed that selected bacteria were able to grow and utilize MSM that contains different concentrations of gasoline. From this data, it can be concluded that oil-degrading bacteria are abundant in soils contaminated with spent oil. Consequently, these data suggest that these microbes could be useful for their application in the biodegradation of contaminated soils.

Biosynthesis of Magnetic Nanoparticles and Their Application in the Biodegradation of Crude Oil-Contaminated sites

Biosynthesis of Magnetic Nanoparticles and Their Application in the Biodegradation of Crude Oil-Contaminated sites

Legacy and dispersant influence microbial community dynamics in cold seawater contaminated by crude oil water accommodated fractions

Dispersants, used for combating oil spills, increase hydrocarbon bioavailability promoting their biodegradation. Oil weathering process introduces harmful soluble hydrocarbons, such as polycyclic aromatic hydrocarbons (PAHs), into the water column, resulting in water-accommodated fraction (WAF). The presence of dispersants can influence the weathering process by increasing PAHs solubility, toxicity and biodegradability. However, little is known on how dispersants affect microbial communities and their degradation capacities, especially in cold environment where low temperature decreases microbial activity and thus hydrocarbon degradation. Here, we investigated the microbial community dynamics in cold water contaminated by WAF prepared from crude oil with or without a commercial dispersant (Finasol OSR52).The WAFs, prepared with Naphthenic North Atlantic crude oil, were used to contaminate seawater from Norwegian cold sites, one oil-contaminated and the other pristine. The WAF-contaminated seawaters were maintained in microcosms at 4 °C for 21 days. The content of PAHs and microbial compositions (16S rRNA gene sequencing) were determined at days 0, 7, 14 and 21. In addition, the 96 h toxicity assay with adult Acartia tonsa revealed WAFs toxicity at days 0 and 21.The toxicity of WAF mixtures, with and without dispersant, against Acartia tonsa was reduced during the experiment, but PAHs removal was not increased. The water from the oil-contaminated site showed the highest PAHs removal revealing legacy effect (presence of microorganisms adapted to PAHs). Additionally, our results reveal: i) microbial community plasticity allowing the adaptation to the presence of PAHs and dispersant, ii) specific bacteria taxa probably involved in PAHs degradation, and iii) dispersants shape the microbial communities dynamics by stimulating potential dispersant-degrading taxa, such as Fusibacter. Thus, our results provide valuable insights on the role of microbial community in determining the fate of water-solubilized hydrocarbon in cold environment while questioning the role of dispersant used for fighting oil spill.

Mixed bacterial consortium can hamper the efficient degradation of crude oil hydrocarbons.

Crude oil degradation efficiency can be improved because of co-metabolism that exists when bacterial consortium is applied. However, because of possible vulnerability to environmental conditions and/or antagonistic interactions among members of the consortium, the degradation efficiency can be hampered. In this laboratory-based study, the biodegradation potentials of pure bacterial isolates namely Pseudomonas aeruginosa strain W15 (MW320658), Providencia vermicola strain W8 (MW320661) and Serratia marcescens strain W13 (MW320662) earlier isolated from crude oil-contaminated site and their consortium were evaluated using 3% crude oil-supplemented Bushnell Haas media. The efficiency was evaluated based on the viable cell count, biosurfactant analyses, percentage hydrocarbon degradation using gravimetric analysis and gas chromatography-mass spectrophotometry (GC-MS) analysis. There was decline in the population of W13 and predominance of W15 in the consortium as the incubation period progressed. Accelerated biodegradation of the crude oil hydrocarbons through co-metabolism was not achieved with the consortium; neither was there any improved resilience nor resistance to environmental changes of strain W13. The GC-MS analyses showed that the highest degradation was produced by W15 (48.23%) compared to W8 (46.04%), W13 (45.24%) and the Consortium (28.51%). The biodegradation of the crude oil hydrocarbons by W15, W8, W13 axenic cultures and their consortium treatments demonstrated that the bacterial constituent in a consortium can influence the synergistic effect that improves bioremediation. Future research that focuses on evaluating possible improvement in bioremediation through maintenance of diversity by continuous bioaugmentation using vulnerable but efficient degraders in a consortium is necessary to further understand the application of consortia for bioremediation improvement.

Assessment of Bilge Water Degradation by Isolated Citrobacter sp. and Two Indigenous Strains and Identification of Organic Content by GC-MS

Bilge water is oily saline wastewater accumulated on the hull at the bottom of a vessel, generated from leakage from pipes and engines and wash-down freshwater containing cleaning solvents. The present study focused on isolating microorganisms from oil-contaminated sites and indigenous species from raw bilge water and assessment of their ability to biodegrade bilge water. Using phenanthrene as a carbon source Citrobacter species was isolated from oil-contaminated sites and its optimum growth condition was found. The results indicated significant tolerance of the bacterium which presented great biodegradation ability for the tested carbon source. At high salinity (33 g L−1 of NaCl), sufficient phenathrene removal was achieved (81%), whereas variation of pH from 5 to 10 did not affected the survival of the microorganism. Regarding the effect of temperature and nutrients, Citrobacter sp. was better adapted at 30 °C, while lack of nutrients presented a negative impact on its growth. Halomonas and Exiguobacterium sp. were isolated from real bilge water using phenanthrene and phenol as a carbon source. The isolated strains independently exposed to high and low range bilge water pointed out around 83% and 53% chemical oxygen demand (COD) removal, respectively. Analysis of untreated bilge water by gas chromatography-mass spectrometry (GC-MS) was carried out, and the results confirmed the presence of organic compounds having a high similarity with Heptane, N-hexadecanoic acid, Methyl isobutyl Ketone and 1-butoxy-2-propanol. Chromatographic analysis of treated bilge water after exposure to isolated strains indicated the existence of new compounds. These metabolites presented high similarity with N-hexadecanoic, methyl ester, N-hexadecanoic and Octadecanoic acid methyl ester.

Continuous VOCs Monitoring in Saturated and Unsaturated Zones Using Thermal Desorber and Gas Chromatography: System Development and Field Application.

Subsurface VOC monitoring has been mainly based on manual sampling, transport, and analysis, which would require a sufficient amount of samples to ensure data accuracy and reliability, and additional costs to ensure sample quality. Therefore, a continuous on-site monitoring system is desirable for accurate measurement and subsequent risk assessment. In this study, benzene, toluene, ethylbenzene, and xylene (BTEX) were continuously monitored by the system based on a thermal desorber (TD) and gas chromatography (GC) in an oil-contaminated site that consisted of saturated and unsaturated zones. For the saturated zone, fully automated groundwater sampling and purging processes were performed, and the gasified samples were applied to the TD–GC system. For the unsaturated zone, the gaseous sample in the site was directly applied to the TD–GC system. After verifying the accuracy and precision of the monitoring system, the continuous monitoring system was successfully operated for more than a month in the field. The monitoring system used in this study is applicable to other sites for continuous monitoring, thus providing a scientific background for advanced risk assessment and policy development.

Evaluation of water quality and ecological risk assessment index from highly oil-contaminated sites in the Niger Delta Nigeria

Multi-element indices in an aquatic ecosystem provide insight into the synergistic effects of many ecological parameters. Using standard analytical techniques and pollution indicators, the eco-toxicological state of oil-contaminated water in three communities in Warri Southwest, Niger Delta, Nigeria, was assessed. Water samples were examined for physicochemical properties, heavy metals, PAH and TPH levels. The ANOVA results showed no significant difference (p >0.05) between the means of the physicochemical parameters and the study stations for the combined parameters. Out of the twenty-five parameters evaluated, the Nemerow Pollution Index (NPI) results revealed thirteen contributing parameters to overall water contamination in the research areas. Conductivity, TSS, TDS, DO, BOD, COD, Oil and Grease, Heavy Metals (Cu, Ni, Mn, and Cd), and Hydrocarbons are among them. These parameters also exceeded the maximum permitted limits set by NESREA. Heavy metal evaluation index (HEI) and geo-accumulation index (Igeo) in water were both found to be high. The PERI (potential ecological risk index) had values >100, indicating a high level of ecological risks. The study areas' overall water quality index (WQI) indicated poor to unsuitable water quality. Water pollution in the selected communities is attributed to various industrial and domestic activities along the waterways, crude oil spills, illegal refining, dredging, and ship and speed boat movement. Periodic monitoring and preventive measures are required in the study areas to keep the aquatic ecosystems from entirely degrading. Adequate legislation and proper effluent management could aid in the prevention of indiscriminate toxic compound discharge into water.

Enhancing rhizoremediation of petroleum hydrocarbons through bioaugmentation with a plant growth-promoting bacterial consortium

The slow rate of natural attenuation of organic pollutants, together with unwanted environmental impacts of traditional remediation strategies, has necessitated the exploration of plant-microbe systems for enhanced bioremediation applications. The identification of microorganisms capable of promoting rhizoremediation through both plant growth-promoting and hydrocarbon-degrading processes is crucial to the success and adoption of plant-based remediation techniques. In this study, through successive enrichments of soil samples from a historic oil-contaminated site in Wietze, Germany, we isolated a plant growth-promoting and hydrocarbon-degrading bacterial consortium dominated by Alphaproteobacteria. In microcosm experiments involving Medicago sativa L. and the isolated bacterial consortium, we examined the ability of the consortium to enhance rhizoremediation of petroleum hydrocarbons. The inoculation of M. sativa with the consortium resulted in 66% increase in plant biomass, and achieved a 91% reduction in diesel fuel hydrocarbon concentrations in the soil within 60 days. Metagenome analysis led to the identification of genes and taxa putatively involved in these processes. The majority of the coding DNA sequences associated with plant growth promotion and hydrocarbon degradation in this study were affiliated to Acidocella aminolytica and Acidobacterium capsulatum indicating their potential for biotechnological applications in the rhizoremediation of sites contaminated by petroleum-derived organic pollutants.

Innovative Methodology for Assessing the Condition, Certification, Systematization and Accounting of Oil-Contaminated Sites

The article describes an innovative method for assessing the condition, certification, systematization and accounting of oil-contaminated sites. The paper offers three-dimensional models, tables on the volume content of petroleum products, tables of the distribution of plots into reclamation groups, QR codes and parcel codes necessary for targeted elimination of the consequences of oil and petroleum products spills in the soil. This technique involves the construction of three-dimensional models of oil-contaminated sites, necessary to reflect the volume of soil contamination, numerical visualization of oil pollution volumes using various data tables, as well as the creation of QR codes and parcel codes, which are necessary to improve the system of accounting, storage and certification of oil-contaminated land.

Population dynamics and crude oil degrading ability of bacterial consortia of isolates from oil-contaminated sites in Nigeria.

Application of bacterial consortium of hydrocarbon degraders to crude oil-contaminated site can enhance bioremediation. This study evaluated the population dynamics and crude oil degradation abilities of various consortia developed from bacterial strains isolated from crude oil-contaminated sites using crude oil-supplemented Bushnell Haas media. Each consortium consisted of three bacterial strains and was designated as Consortium A (Serratia marcescens strain N4, Pseudomonas aeruginosa strain N3R, Pseudomonas aeruginosa strain W11), B (Pseudomonas aeruginosa strain N3R, Pseudomonas aeruginosa strain W11, Pseudomonas protegens strain P7), C (Serratia marcescens strain N4, Pseudomonas aeruginosa strain W11, Pseudomonas protegens strain P7), and D (Pseudomonas aeruginosa strain W15, Providencia vermicola strain W8, Serratia marcescens strain W13). There was progressive decline in the populations of Serratia marcescens strains in the consortia as the incubation period progressed. This may have led to reduction in their synergistic contribution and, subsequently, total degradation ability of crude oil by the consortia. The gravimetric analyses showed that Consortium D produced the highest % crude oil degradation of 29.66% compared to Consortia A, B, and C with 23.73%, 11.86%, and 19.49% respectively. Based on gas chromatography-mass spectrometry analyses, Consortium D produced the highest percentage total petroleum hydrocarbon degradation of 73.65% compared to 68.24%, 68.94%, and 69.19% produced by Consortia A, B, and C respectively. The biodegradation potential of Consortium D also demonstrates the significance of using isolates from the same isolation site in development of consortium for bioremediation.

Production optimization, stability and oil emulsifying potential of biosurfactants from selected bacteria isolated from oil-contaminated sites.

Oil pollution is of increasing concern for environmental safety and the use of microbial surfactants in oil remediation has become inevitable for their efficacy and ecofriendly nature. In this work, biosurfactants of bacteria isolated from oil-contaminated soil have been characterized. Four potent biosurfactant-producing strains (SD4, SD11, SD12 and SD13) were selected from 27 isolates based on drop collapse assay and emulsification index, and identified as species belonging to Bacillus, Burkholderia, Providencia and Klebsiella, revealed from their 16S rRNA gene-based analysis. Detailed morphological and biochemical characteristics of each selected isolate were determined. Their growth conditions for maximum biosurfactant production were optimized and found quite similar among the four isolates with a pH of 3.0 and temperature 37°C after 6 or 7 days of growth on kerosene. The biosurfactants of SD4, SD11 and SD12 appeared to be glycolipids and that of SD13 a lipopeptide. Emulsification activity of most of the biosurfactants was stable at low and high temperatures (4–100°C), a wide range of pH (2–10) and salt concentrations (2–7% NaCl). Each biosurfactant showed antimicrobial activity against two or more pathogenic bacteria. The biosurfactants were well-capable of emulsifying kerosene, diesel and soya bean, and could efficiently degrade diesel.

Phylogeny and polycyclic aromatic hydrocarbons degradation potential of bacteria isolated from crude oil-contaminated soil in Diyarbakir, in the southeast of Turkey

In the present study, four indigenous bacteria designed as OACR6-OACR9 capable of degrading Polycyclic Aromatic Hydrocarbons (PAHs) were isolated from oil-contaminated soils in Diyarbakir city, in Turkey. 16S rRNA gene analysis revealed that strain OACR6 indicated 99.78% homology to Bacillus megaterium NBRC 15308 = ATCC 14581. OACR7, OACR8 and OACR9 strains were found to be members of the Sphingobacterium genus according to genetic analysis. It was observed that the OACR7 and OACR8 strains were 96.63% and 96.94% similar to Sphingobacterium multivorum strain IAM 14316, respectively. On the other hand, strain OACR9 indicated 96.79% homology to Sphingobacterium siyangense strain SY1 16S. GC-MS analyzing revealed that strain OACR6 was able to degrade 68.7% of fluorene and 69.8% of phenanthrene compared to the controls, strain OACR7 was able to degrade 67.5% of fluorene and 65.9% of phenanthrene, strain OACR8 was able to degrade 74.4% of fluorene and 76.4% of phenanthrene and strain OACR9 was found to be able to degrade 67.9% of fluorene and 69.8% of phenanthrene. The findings of this study indicate that the strains investigated have bioremediation potential at oil-contaminated sites and to our knowledge, this is the first study on the biodegradation of PAHs in the oil-contaminated areas in Diyarbakir.