Microbial Community Profiling of Active Oleophilic Bacteria involved in Bioreactor-based Crude-oil Polluted Sediment Treatment

Purpose: At elevated salinities conventional microbiological processes are not very effective, therefore clean up of contaminants using bioremediation strategy will involve the use of halophilic and halo-tolerant bacterial species. This research therefore aimed at isolating and identifying potential halophilic and halo-tolerant bacterial species capable of hydrocarbon degradation during bioreactor based treatment with exogenous nutrients. Methods: The diversity of indigenous bacterial species with potential to degrade hydrocarbons was investigated using both culture-dependent and independent techniques. Bioremediation of hydrocarbon contaminated saline sediments was carried out using seven 2.5 liter bioslurry bioreactors operated over a 64-day period. Physicochemical parameters monitored were pH, nitrate, phosphate, total petroleum hydrocarbon (TPH), polycyclic aromatic hydrocarbon (PAH), temperature, salinity, and total organic carbon (%TOC). Results: The baseline TPH, PAH and pH of the sediments were 19 ppm, 3.1 ppm and 7.0 respectively. The baseline salinity of the sediment was 10% thus the sediment was adjudged moderately saline. TPH ranged from 97 ppm-105 ppm on day zero and decreased to an average of 5.62 ppm on day 64, while PAH ranged from 56 ppm-61 ppm on day zero and decreased to an average of 4.02 ppm on day 64. The bacterial species identified as potential hydrocarbon degraders includes Halomonas lutea, Achromobacter spp, Aquitalea magnusonii, Bacillus sp, Sphingobacterium sp, Shewanella sp, Brevundimonas naejangsanensis, Pseudomonas pseudoalcaligenes, Pseudomonas aeruginosa, unidentified bacterium BH23 and Gordonia sp. The genus Pseudomonas formed majority of the isolates successfully sequenced and exhibited similarity values ranging from 91% to 100% with sequences deposited in GenBank. A combination of both molecular and culture based technique allowed the identification to species level of twelve isolates. One isolate could not be identified while the remaining isolates were identified to their generic level. Treatment BCD recorded highest total culturable heterotrophic bacteria (TCHB) count (7.1 × 108 cfu/g) and total culturable hydrocarbon utilizing bacteria (TCHUB) count (6.7 × 108 cfu/g). There was a significant difference at P<0.05 in TCHUB bacteria counts between the unamended bioreactor slurries and those amended with organic and inorganic nutrients. There were also significant differences in TCHUB counts when the bioaugumented slurry was compared with those amended with NPK, Urea and cow dung using one way ANOVA and Tukey’s multiple comparison tests. Conclusion: This study revealed potentially novel bacterial species and previously described hydrocarbon degrading bacterial species that can be characterized further to determine their role in hydrocarbon degradation as well as their salt tolerance level prior to application in bioremediation of saline environments.

The presence of polycyclic aromatic hydrocarbons (PAH) from crude oil and gas condensate, ferrochrome lignosulphate and lead compounds in drill cuttings and drilling mud additives are of environmental concern during exploration and development drilling operations. These environmental toxicants encountered during drilling operations were reason for carrying out this study. This research was tailored toward adopting scientific and technological method that is efficient and cost effective in reducing these chemical toxicants in the environment below the acceptable limit in order to have sustainable environment and achieve millennium goal on environment. This target was achieved by stimulating the hydrocarbon utilizing bacteria associated with drill cuttings for degradation of PAH and TPH. The physiochemical parameters supporting the proliferation of the hydrocarbon utilizing bacteria were determined. Microbial populations, total petroleum hydrocarbon (TPH) and PAH were monitored at intervals throughout the period of the study. Drill cutting (Dc) from oil well in Usan field was sampled for treatment using bioremediation technology. The five treatment options designated Dc, Dc +S, Dc+F, Dc+S+F+D and Dc + D were set in triplicates in different cells using plastic bowls. A total of 15 plastics bowls of 35cm in diameter by 11cm depth were used. The setup was sampled repeatedly at intervals for analysis within the study period. Four treatment options were biostimulated with soil(S), NPK fertilizer (F), or gold crew dispersant (D) while unamended (Dc) and heat-treated (hDc) options served as controls. For each treatment option, 2kg (wet weight) of drill cutting was amended with 40g of treatment material. The bioremediation process was investigated in a 56-day study period. Unamended treatment (Dc) had the highest heterotrophic bacterial count (4.5 x 105cfu/g) on day 0 while Dc+D had the lowest count (3.0 x 103 cfu/g) on day 56. The hydrocarbon utilizing bacterial count showed that Dc +D had both the highest (6.5x 103 cfu/g) on day 28 and also the lowest count (2.6 x 102cfu/g ) on day 56. For all the treatment options on day 0 the total petroleum hydrocarbon (TPH) ranged from 33.22 to 46.00 mg/kg while polycyclic aromatic hydrocarbons (PAH) ranged from 3.51 to 6.4mg/kg. In all the treatment option by day 56, the TPH was <8.0mg/kg and PAH <2.5mg/kg. By day 56, the percentages of biodegradation of TPH as measured with GC-FID were Dc(71.82%), Dc+S(77.09%),Dc+F(83.58%), Dc+S+F+D(79.95%), Dc+D(81.58%) and heat-treated (30.56%). PAH percentage degradation rates were as follows: Dc (49.92%), Dc+S (52.35%), Dc+F (86.09%), Dc+S+F+D (64.74%), Dc+D (74.20%) and heat-treated (2.23%). Dc+F gave the highest percentage degradation for both TPH and PAH. Fifty-two hydrocarbon utilizing bacterial isolates were obtained. The bacterial isolates were Bacillus spp.(26.92%),Proteus Sp.(1.92%), Pseudomonas spp.(7.46%), Alcaligenes spp.(5.77%), Micrococcus spp(7.55%), Acinetobacter sp(1.92%), Aeromonas spp (21.15%) and unidentified (28.85%). Screen test, for degradative potential of the isolates indicated that many of the bacterial isolates had hydrocarbon degradative potential. This result showed that the drill cuttings investigated could be remediated using microbial agents and that environmental factor (abiotic factors) had a role to play in hydrocarbon alternation as shown in the heat –treated control.

The biodegradation of polycyclic aromatic hydrocarbons by associated microorganisms were studied. Soil and waste water samples were collected from four abattoirs located at Egbu and Ogbe in Imo state, Trans-Amadi and Ahoada in Rivers State. Likewise, surface water and sediment samples from Otamiri River and Oginigba Creek adjoined to Egbu and Trans-Amadi abattoirs, respectively were collected using standard methods. The ability of hydrocarbon utilizing bacteria and fungi to biodegrade polycyclic aromatic hydrocarbons (PAHs) was carried out by growing the isolates in a mineral salt broth amended with PAHs and nutrients (NPK fertilizer and cow dung). Levels of polycyclic aromatic hydrocarbons (PAHs) left after incubation were determined using Gas chromatographic method. Results showed that soil samples from various abattoirs had high concentrations of PAHs ranging from 0.176 mg/kg at Ahoada abattoir to 2.44 mg/kg at Egbu abattoir. In a 21-day biodegradation test, there was a drop in the initial concentration of PAHs used as control from 0.03 mg/l to 0.024 mg/l. There was loss of low molecular weight PAHs than the high molecular weight components. It is evident from the study that both mixed cultures of bacteria and fungi can biodegrade polycyclic aromatic hydrocarbons. Results from this study have shown that abattoir wastes have high pollution strength and thus should be treated before being discharged into the environment. Of note is the fact that the microorganisms isolated from the abattoirs are potential agents of remedying environments impacted by polycyclic aromatic hydrocarbons (PAHs).

The use of environmentally friendly fertilizers is a new strategy to subside the undesirable effect of chemical fertilizers. The field experiment was conducted to investigate the effect of cow manure and NPK fertilizers on physiochemical characteristics and nutrients accumulation of Satureja macrantha L. in a randomized complete block design (RCBD) in three replications. Cow manure and NPK (20, 20, 20) were used in four levels as cow manure (60 t ha-1), NPK fertilizer, combined cow manure (30 t ha-1) and NPK (50: 25: 25 kg ha-1) fertilizer (, and untreated treatment (control) in Karaj, Iran, during 2017 and 2018. The results showed increased dry weight yield under manure or the combined NPK and manure fertilizers in second year. The relative water content (RWC) in second-year plants treated with manure was higher compared to other experimental treatments. The EO percentage increased by manure application and its combination with NPK fertilizer, ranging from 1.06 to 1.86%. EO yield of aerial parts of S. macrantha under organic manure in the second year was significantly higher in comparison with control and NPK-treated plants. The GC/MS analysis showed that the main EO compounds of S. macrantha L. were p-cymene (22.14%-33.78%), γ-terpinene (21.7%-35.22%), and thymol (13.1%-37.9%). The minerals in aerial parts of S. macrantha were changed under fertilizers and year. Manure and its combination with NPK fertilizer significantly improved phosphorus (P), and potassium (K). Both NPK fertilizer and cow manure significantly led to increased Ca concentration in second-year plants. NPK fertilizer had negative effect on Fe in second-year plants, but the enhanced Fe was observed in the second year when plants treated with cow manure. The present study recommended the combined use of manure and NPK fertilizers to reach the optimum EO of S. macrantha L.

The Great Artesian Basin (GAB) is a vast subterranean thermal aquifer system underlying over 20% of the Australian continent. Substantial reserves of oil, gas and minerals exist within the GAB and combined with industrial activities can often contaminate the groundwaters. The current study investigated the bacterial ecology of bore waters that were in or close to oil deposits. Three sites were selected, two in the Quilpie/Eromanga region of Queensland (Naretha bore registered number 4022 and Adavale bore registered number 305), and the other in the Moomba oil field of South Australia (Moomba bore 9). A wide diversity of bacteria was detected across all of the samples collectively, including members of 32 bacterial phyla. There was greater diversity in the water samples from bores 4022 and 305 compared with Moomba 9, which was likely due to its closer association with oil. The most dominant bacterial taxa were similar in bores 4022 and 305, families Rhodobacteraceae, and Xanthomonadaceae and the order Bacillales. In contrast, the dominant taxa from Moomba 9 were the family Oxalobacteriaceae and the genus Agrococcus. Three different water samples were tested from bore 4022, from the source, 100 m and 250 m downstream in the runoff channel water. The bacterial diversity increased the further away the water flowed from the bore, due to the cooler water and contamination from the surrounding environment. A comprehensive anaerobic thermophilic enrichment program revealed that bacteria grew on a wide variety of organic substrates and a range of heavy metals as terminal electron acceptors. Isolation yielded 164 bacteria capable of using substrates from sugars and extracts through to polycyclic aromatic hydrocarbons (PAH) and reducing the metals iron(III), vanadium(V), cobalt(III) and manganese(IV). Seven pure iron(III) reducing polycyclic aromatic hydrocarbon (PAH) degrading bacteria, designated strains RN40AT, RN40BT, RN40CT, RN40DT, RN305AT, RN305BT and MBA9BT, were selected for further studies. The rates of degradation Polycyclic Aromatic Hydrocarbon Degradation by Anaerobic Bacteria from the Great Artesian Basin and PAH preference varied significantly between the isolates. Strain MBA9BT showed the highest extent (97.6%) of anthracene degradation while strain RN305BT was the lowest (9.7%). Again, strain MBA9BT also showed the highest extent (91.2%) of pyrene degradation and strain RN40DT showed the lowest (16.1%). Phenanthrene degradation was highest in strain RN40BT and the lowest in strain MBA9BT (2%). PAH degradation in all the isolates showed a direct dependence on Fe(III) reduction. A measurable decrease in the surface tension of the medium suggested the production of biosurfactants by all isolates when grown with PAHs as substrates. Genomic analysis of the isolates revealed subsystems of different pathways that are commonly found in metal acquisition, transport and utilisation as well as those for aromatic hydrocarbon degradation. Strain RN40DT had the highest number of genes involved in the metabolism of PAHs, though all of the isolates had genes for the metabolism of central aromatic intermediates, especially those related to catechol, salicylate and homogentisate degradation. The isolates had varying levels of genes involved in the metabolism and resistance to iron, copper, chromium, zinc, molybdenum, manganese and mercury. Strains RN40AT, RN305AT RN305BT, RN40BT and RN40DT contained the most genes for iron acquisition and metabolism including those for siderophores, hemin transporters and ferric ABC transport systems. The results in the current study have built upon our understanding of bacterial diversity in the GAB, particularly with insights into waters associated with oil deposits. Bacteria that degrade polycyclic aromatic hydrocarbons with the simultaneous reduction of Fe(III) under anaerobic conditions were isolated for the first time and may have significant potential in bioremediation of contaminated groundwaters.

Finding an environment-friendly and affordable method to remove contaminated soils from Polycyclic Aromatic Hydrocarbons (PAHs) has now become an attractive field for researchers, with super-critical fluid extraction being an innovative process in the field of contaminated soil treatment. Extraction with super-critical fluid is a simple and rapid extraction process that uses super-critical fluids as solvents. The present study has investigated the extraction of contaminated soil with Polycyclic Aromatic Hydrocarbons (PAHs) by means of batch supercritical water reactor, employing variables like pressure (100–300 bar), temperature (60–140 ◦C), residence time (0.5–3 hours), and base, acidic, and neutral pH values. In order optimize the process parameters, Response Surface Methodology (RSM) has been used. Results show that removal efficiency of PAHs is between 82%-100%, where the highest PAHs removal efficiency (100%) has been observed in Test No. 22, with a pressure of 300 bars, temperature of 500°C, acidic pH equal to 5, and duration of 3 hours. In addition, the lowest removal efficiency of these compounds (82%) has been obtained in Test No. 26, with a pressure of 300 bars, temperature of 350°C, base pH of 9, and duration of half an hour. According to the results from this study, it has become clear that residence time is the most important and most effective parameter for removing PAHs from contaminated soil. Afterwards, temperature and pH are most influential with pressure showing the least effect. Using supercritical water method in appropriate conditions can eliminate more than 99% of aromatic contamination.

The research objective was to study the effect of organic and inorganic fertilizer on the growth and production of lettuce. This research was conducted from February 2017 to April 2017 at Green House, Faculty of Agricultural,Sjakhyakirti University Palembang. The research used Randomized Block Design (RAK) with 12 treatments and repeated 3 times. The treatment in this research was K (50 g.crop-1 cowmanure and 0 g.crop-1NPK fertilizer), L (50 g.crop-1 cow manure and 1 g.crop-1 NPK fertilizer ), M (50 g.crop-1 cow manure and 2 g.crop-1 NPK fertilizer), N (50 g.crop-1 cow manure and 3 g.crop-1NPK fertilizer), O ( 80 g.crop-1 cow manure and 0 g.crop-1 NPKfertilizer), P (80 g.crop-1 cow manure and 1 g.crop-1 NPK fertilizer), Q (80 g.crop-1 cow manure and 2 g.crop-1NPK fertilizer), R (80 g.crop-1 cow manure and 3 g.crop-1NPK fertilizer), S (110 g.crop-1 cow manure and 0 g.crop-1 NPK fertilizer), T (110 g.crop-1 cow manure and 1 g.crop-1NPK fertilizer), U (110 g.crop-1 cow manure and 2 g.crop-1 NPK fertilizer), V (110 g.crop-1 cow manure and 3 g.crop-1 NPK fertilizer). The variables observed in this study were plant height (cm), number of leaves (strands), number of roots, wet weight of plant (g), dry weight of plant (g). The results showed that the organic fertilizer of cow manure and inorganic NPK fertilizer have no significant effect on the growth but has a significant effect on the production of lettuce plant. However, the U (110 g.crop-1 cow manure and 3 g.crop-1 NPK fertilizer) showed the best production of many leaves and wet trimming weight of lettuce.

A small-scale functional gene array containing 15 functional gene probes targeting aliphatic and aromatic hydrocarbon biodegradation pathways was used to investigate the effect of a pilot-scale air sparging and nutrient infiltration treatment on hydrocarbon biodegradation in creosote-contaminated groundwater. Genes involved in the different phases of polycyclic aromatic hydrocarbon (PAH) biodegradation were detected with the functional gene array in the contaminant plume, thus indicating the presence of intrinsic biodegradation potential. However, the low aerobic fluorescein diacetate hydrolysis, the polymerase chain reaction (PCR) amplification of 16S rRNA genes closely similar to sulphate-reducing and denitrifying bacteria and the negligible decrease in contaminant concentrations showed that aerobic PAH biodegradation was limited in the anoxic groundwater. Increased abundance of PAH biodegradation genes was detected by functional gene array in the monitoring well located at the rear end of the biostimulated area, which indicated that air sparging and nutrient infiltration enhanced the intrinsic, aerobic PAH biodegradation. Furthermore, ten times higher naphthalene dioxygenase gene copy numbers were detected by real-time PCR in the biostimulated area, which was in good agreement with the functional gene array data. As a result, functional gene array analysis was demonstrated to provide a potential tool for evaluating the efficiency of the bioremediation treatment for enhancing hydrocarbon biodegradation in field-scale applications.

حذف هیدروکربن‌های نفتی از آب آلوده به‌صورت سنتزی در یک فتورآکتور خورشیدی در حضور نانوذرات TiO2 پوشش یافته بر صفحات بتنی انجام گردید. فتورآکتور مورد استفاده شامل یک مخزن ذخیره به حجم 60 لیتر همراه با پمپ شناور، سیستم پلکانی با 5 عدد پلۀ تثبیت‌شده با نانو TiO2، یک سرریز به حجم 5 لیتر در بالای پلکان و شاسی فلزی با ملحقات آن بود. در این رآکتور بخش ماورای بنفش (UV) نور خورشید به‌عنوان منبع تأمین انرژی به‌جای لامپ UV استفاده شد. پارامترهای بهینۀ حاصل pH برابر 5، بارگذاری جرمی TiO2 60 گرم بر متر مربع، مدت زمان تابش UV معادل 200 دقیقه، غلظت اولیه 100 میلی‌گرم بر لیتر و غلظت H2O2 برابر 2000 میلی‌گرم بر لیتر بودند. نتایج نشان داد که در شرایط بهینه راندمان حذف COD، مجموع هیدروکربن‌های نفتی (TPH) و هیدروکربن‌های چندحلقوی (PAHs) به‌ترتیب برابر با 48/70، 63/67 و 75/84 درصد می‌باشد. هم‌چنین نتایج آزمایش GC-FID در شرایط بهینه نشان داد که بیشتر هیدروکربن‌های حذف‌شده از نوع پلی‌آروماتیک بودند و آن‌چه باقی‌ماند از نوع هیدروکربن‌های بدون خطر آلیفاتیک بود.

&#x0D; &#x0D; &#x0D; The study assessed the removal of total petroleum hydrocarbon (TPH) and polyaromatic hydrocarbons (PAHs) from spent engine oil (SEO) contaminated soil through bioenhancement of bacteria isolated from SEO polluted soil. Sterilized soil was subjected to a three level of SEO contamination before the addition of sterilized biostimulants including powdered cow dung (CD), powdered cocoa pod husk (CPH) and compost (made from fresh CPH and CD). Bacterial inoculum being Staphylococcus aureus and Bacillus cereus co-culture (150 mL) was added to the mixture in polyethylene bags. It was a factorial experiment that was laid out in a completely randomized design (CRD). The TPH and PAHs were estimated in the first day, fifth week and the tenth week that the room incubation lasted. Results generated from the influence of biostimulants on TPH and PAHs degradation potential of the bacterial co-culture showed that degradation of the hydrocarbon contents was significantly enhanced (p &lt; 0.05). At the tenth week, compost enhanced the most TPH reductions (315 and 380 mg kg–1) compared with other biostimulants on 5% and 15% SEO contamination levels, respectively. Compost equally enhanced the most PAHs reductions (48.8, 39.6 and 94.6 mg kg–1) compared with other biostimulants on 5%, 10% and 15% SEO contamination levels respectively. However, the quantity of SEO contents degraded was significantly higher in the bioaugmented and biostimulated soil samples compared with the control employed. The technology adopted in this study can be effectively employed for the bioremediation of petroleum hydrocarbon related pollution.&#x0D; &#x0D; &#x0D;

Crude oil contamination poses significant ecological and agricultural challenges, particularly in oil-producing regions such as Nigeria's Niger Delta. The persistence of toxic petroleum hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs), adversely affects soil health, plant growth, and food security. Rich in essential nutrients, cow dung enhances the growth and activity of oil-degrading microorganisms such as Marinobacter spp. and Pseudomonas spp., promoting the breakdown of these hydrocarbons. Hence, the objective of this paper was to evaluate the bioremediation efficacy and total petroleum hydrocarbon (TPH) reduction in crude oil contaminated soil using cow dung using appropriate standard methods. Data obtained indicates a reduction range of between 54.48 - 60.19% of total petroleum hydrocarbon (TPH) content in the crude oil contaminated soil after bioremediating with the cow dung. This result is attributed to increased nutrient availability and improved oxygen diffusion associated with optimal amendment rate. In comparison, natural attenuation in untreated soil achieved only a 17.22% reduction. This approach aligns with Sustainable Development Goals (SDG 12 and SDG 15) which is to promote responsible waste utilization and ecosystem restoration. The findings underscore cow dung's viability as an eco-friendly and cost-effective strategy for mitigating the environmental impacts of crude oil pollution.

This study involved the design and fabrication of airlift fermenters for the mass propagation of a consortium of three microorganisms (Pseudomonas aeruginosa, Pseudomonas fluorescence and Aureobasidium pullulans). The efficacy of the blend in the bioremediation of simulated crude oil polluted water systems environments was also tested with a view to generating more data on crude oil degrading microorganisms for bioremediation purposes. The organisms were separately grown on a gyratory shaker at 120 rpm and at 30 °C until notable growths were observed. Equal volume of the grown organisms (500 ml) of mixed culture was used as inoculum for the 4.5 L of medium in the 7 L airlift fermenter. Thereafter, this was transferred into the 45 litres medium in the 70 L fermenter until significant growth was observed at room temperature. Culture broths were withdrawn at intervals for the determination of biomass and residual hydrocarbon concentrations. The product from the 70 L fermenter was introduced into simulated polluted water systems from which samples were withdrawn weekly. Analyses for residual hydrocarbon contents were carried out using appropriate analytical techniques. The results showed that 78.5% hydrocarbon removal was observed in the 7 L fermenter after 72 h, while that of the 70 L fermenter was 97.8% after 180 h of fermentation. Polluted water sample treated with the microbes experienced 96.4% removal after 10 weeks of treatment. It was observed further that the application of NPK fertilizer biostimulant aided microbial activities in the removal of petroleum hydrocarbons than urea, cow dung and poultry droppings. The study has demonstrated that effective bioremediation of crude oil polluted water systems could be achieved through the application of biostimulants with mass propagated crude oil degrading organisms using airlift fermenter systems. Keywords: Pseudomonas aeruginosa; Pseudomonas fluorescence; Aureobasidium pullulans; Airlift fermenter; Bioremediation; Biostimulation; Bioaugmentation.

This study was conducted at the Agricultural Extension Center in Galesong from July to September 2022 to examine the effects of a combination of cow and goat manure, as well as NPK fertilizer, on the growth and yield of sweet corn. The study used a factorial Randomized Block Design (RBD) with two factors: the combination of cow and goat manure (no manure, 5, 7.5, and 11.5 tons/ha) and NPK fertilizer (100, 200, and 300 kg/ha), resulting in 12 treatment combinations with 36 experimental units. Results indicated that a combination of 10 tons/ha cow manure and 15 tons/ha goat manure improved plant height, leaf number, fresh cob weight per plant, and yield per hectare. NPK fertilizer at 300 kg/ha increased plant height, cob length, and fresh cob weight per plot, with no significant interaction between the combination of manures and NPK fertilizer on sweet corn growth and yield.

Environmental pollution caused by the release of a wide range of xenobiotic compounds has assumed serious proportions. Bioremediation techniques, utilizing microorganisms to reduce the concentration and toxicity of various chemical pollutants such as petroleum hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, industrial solvents and pesticides, are the most promising strategies for the restoration of polluted environments. Several bacterial strains with promising degradative abilities have already been isolated and characterized. However, the full exploitation of the potential of bioremediation strategies requires not only the isolation of a large number of strains with wide degradative abilities but also an accurate characterization of these strains both at the microbiological and biochemical/genetic level. This knowledge is necessary to perform a rational planning of bioremediation interventions. The present work describes isolation of new strains able to degrade aromatic hydrocarbons directly from polluted environments by means of appropriate selection procedures. Novosphingobium sp. PP1Y, isolated from a surface seawater sample collected from a closed bay in the harbor of Pozzuoli (Naples, Italy), uses fuels as its sole carbon and energy source. Like some other Sphingomonads, this strain can grow as either planktonic free cells or sessile-aggregated flocks. In addition, this strain was found to grow as biofilm on several types of solid and liquid hydrophobic surfaces including polystyrene, polypropylene and diesel oil. Strain PP1Y is not able to grow on pure alkanes or alkane mixtures but is able to grow on a surprisingly wide range of aromatic compounds including mono, bi, tri and tetracyclic aromatic hydrocarbons and heterocyclic compounds. During growth on diesel oil, the organic layer is emulsified resulting in the formation of small biofilm-coated drops, whereas during growth on aromatic hydrocarbons dissolved in paraffin the oil layer is emulsified but the drops are coated only if the mixtures contain selected aromatic compounds, like pyrene, propylbenzene, tetrahydronaphthalene and heterocyclic compounds. These peculiar characteristics suggest strain PP1Y has adapted to efficiently grow at the water/fuel interface using the aromatic fraction of fuels as the sole carbon and energy source. The whole PP1Y genome sequence could provide clues about the metabolism of this species and about the possibility of manipulating it for bioremediation purposes. The PP1Y genome is comprised of a single 3.9 Mbp circular chromosome and of 3 plasmids, one megaplasmid (Mpl; 1.16 Mbp), one large plasmid (Lpl; 0.19 Mbp), and one small plasmid (Spl; 0.05 Mbp). Notably, this is the first time that a megaplasmid of such size has been identified in a sphingomonad. Our results will help to clarify the molecular basis of the unusual features of this strain and to engineer strains with enhanced cultural and bioremediation abilities.

Adsorption of polycyclic aromatic hydrocarbons (PAHs) in water using the packed column of zero-valent iron was investigated in this study. The effects of the ratio of iron powder and quartz sand, the filling height of the column, retention time and pH of PAHs solution in the column on PAH adsorption were evaluated. Furthermore, the competitive adsorption of PAHs, the maximum capacity for PAHs adsorption, iron dissolution, and recycled utilization of the column also was also investigated. The results show that the mass ratio of zero-valent iron and quartz sand was the best at 9:1. When the filling height increased, the capacity for adsorption of PAHs got greater, and the desorption of PAHs would be much more difficult. The adsorption rate increased with the retention time of PAHs solutions in the column, and then reduced gradually with the retention time. The capacity for PAHs adsorption was stronger under neutral or alkaline conditions, but was weaker under the acid system. When multiple PAHs were mixed together, the competitive adsorption of PAHs was obvious at high concentrations, but not evident at low concentration. The adsorption rates of the high-ring PAHs were higher than those of the low-ring PAHs. Maximum capacity for PAHs adsorption in water reached at 0.015 g·g-1. When the mass content of PAHs was 25 μg, the penetration volume of water was up to 4 L. The packed column was re-activeted with 0.1% H2O2 under the acidic system, and the variability of adsorption rate was less than 3% when it was reused. Therefore, it is an effective way of removing PAHs from water by the packed column of zero-valent iron, which may have a better prospect in large-scale application.