Preliminary study on biodegradation of phenanthrene by bacteria isolated from mangrove sediments in Hong Kong

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous persistent environmental contaminants generated by natural combustion processes and human activities. PAHs are considered hazardous because of cytotoxic, mutagenic, and carcinogenic effects. Sixteen individual PAH compounds have been identified as priority pollutants by the United States Environmental Protection Agency (U.S. EPA). All substances originated in to the environment by either biogenic or anthropogenic sources. Anthropogenic compounds describe synthetic compounds, and compound classes as well as elements and naturally occurring chemical entities which are mobilized by man’s activities. In the marine environment, the fate of pollutants is largely determined by biogeochemical process. Some of these chemical changes enhance the toxicity of the pollutants. Other chemical changes cause the degradation or immobilization of pollutants and, as a result, act to purify the waters. Possible fates for PAHs, released into the environment, include volatilization, photo-oxidation, chemical oxidation, bioaccumulation and adsorption on soil particles, leaching, and microbial degradation. Elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) have been found in mangrove sediments due to anthropogenic compounds.

PAHs contamination and bacterial communities in mangrove surface sediments of the Jiulong River Estuary, China

The concentrations of total polycyclic aromatic hydrocarbons (PAHs) and 22 individual PAH compounds in 42 surface sediments collected from the mangrove forest of Qeshm Island and Khamir Port (Persian Gulf) were analyzed. PAHs concentrations ranged from 259 to 5,376 ng g(-1) dry weight with mean and median values of 1,585 and 1,146 ng g(-1), respectively. The mangrove sediments had higher percentages of lower molecular weight PAHs and the PAH profiles were dominated by naphthalene. Ratio values of specific PAH compounds were calculated to evaluate the possible source of PAH contamination. This ratios suggesting that the mangrove sediments have a petrogenic input of PAHs. Sediment quality guidelines were conducted to assess the toxicity of PAH compounds. The levels of total PAHs at all of stations except one station, namely Q6, were below the effects range low. Also, concentrations of naphthalene in some stations exceeded the effects range median.

Research on polycyclic aromatic hydrocarbons (pah)s compound at Jakarta Bay seawater were carried out on July 2011. The objectives of this research were to measure the concentration of total polycyclic aromatic hydrocarbons (PAH) compound, concentration of individual PAH compound, and to identify sources of PAH compound in seawater. PAH compound concentration was measured by Gas Chromatography (Gas Chromatography-Flame Ionization Detector) and sources of polycyclic aromatic hydrocarbons compound were identified by diagnostic ratio analysis. The results show that the concentration of PAH compound in the middle of Jakarta Bay was higher compared to the west and the east. In the west and middle of Jakarta Bay, it is found that 11 PAH types, and 10 types in the east. Individual PAH compound dominated by high moleculer weight of PAH Benzo(a)Anthracene, Chrysene, Benzo(b)Fluoranthene, Benzo(a)Pyrene, dan Indeno(123-cd) Pyrene. The results of PAH compound ratio individual analysis showed that polycyclic aromatic hydrocarbons compound at Jakarta Bay seawater came from oil spill and incomplete combustion mixture of organic material such as wood, grass, fuel oil, and fuel industry combustion activity.

Biodegradation of mixed polycyclic aromatic hydrocarbons by pure and mixed cultures of biosurfactant producing thermophilic and thermo-tolerant bacteria

Concentrations of polycyclic aromatic hydrocarbons (PAH) were studied in 36 sediment samples collected from 29 sites in the central Adriatic Sea. The total concentration of PAH showed high variability, ranging from 42.85 µg kg−1 in open sea sediments to 28,662 µg kg−1 in the sediments of Šibenik Bay. Unsubstituted, parent PAH were dominant PAH compounds in the entire area of Šibenik Bay and most of the stations in the coastal area. In Kaštela Bay, methyl PAH concentrations were higher than the concentrations of unsubstituted PAH, whereas in the sediments along the mid-Adriatic transect, similar concentrations of both PAH fractions were determined. PAH sources were investigated by applying the Positive Matrix Factorization software developed by the U.S. Environmental Protection Agency (USEPA). The results indicate the presence of four sources, two of which can be considered petrogenic and two pyrogenic. The contribution of the sources to the total concentration PAH at each station indicates the dominance of pyrogenic sources in Šibenik Bay and at most stations in the coastal area. In the sediments along the mid-Adriatic transversal, as well as in Kaštela Bay, PAHs originate mainly from petrogenic sources. The obtained results show that PMF can be a suitable tool for control of PAH pollution and thus, for the management of various activities in the Adriatic region. Seasonal differences between the contributions of sources in the Kaštela and Šibenik bays indicate that the contribution of traffic to the total concentration of PAH was higher during the tourist season. The carcinogenic risk of PAH determined by toxicity equivalent (TEQ) calculations showed an increased carcinogenic risk in the whole area of Šibenik Bay, regardless of the number of PAH compounds considered for the calculations. A low PAH-related carcinogenic risk was found for the rest of the study area.

Bioaugmentation effectively enhances microbial bioremediation of hazardous polycyclic aromatic hydrocarbons (PAHs) from contaminated environments. While screening for pyrene-degrading bacteria from a former manufactured gas plant soil (MGPS), the mixed enrichment culture was found to be more efficient in PAHs biodegradation than the culturable pure strains. Interestingly, analysis of 16S rRNA sequences revealed that the culture was dominated by a previously uncultured member of the family Rhizobiaceae. The culture utilized C1 and other methylotrophic substrates, including dimethylformamide (DMF), which was used as a solvent for supplementing the culture medium with PAHs. In the liquid medium, the culture rapidly degraded phenanthrene, pyrene, and the carcinogenic benzo(a)pyrene (BaP), when provided as the sole carbon source or with DMF as a co-substrate. The efficiency of the culture in the bioremediation of PAHs from the MGPS and a laboratory waste soil (LWS) was evaluated in bench-scale slurry systems. After 28 days, 80% of Σ16 PAHs were efficiently removed from the inoculated MGPS. Notably, the bioaugmentation achieved 90% removal of four-ringed and 60% of highly recalcitrant five- and six-ringed PAHs from the MGPS. Likewise, almost all phenanthrene, pyrene, and 65% BaP were removed from the bioaugmented LWS. This study highlights the application of the methylotrophic enrichment culture dominated by an uncultured bacterium for the efficient bioremediation of PAHs.

The current study aimed to envisage the spatial and seasonal distribution of the six polycyclic aromatic hydrocarbons (PAHs) in the soil samples collected in the proximity of the brick kilns in Balochistan, Pakistan. Soil samples were collected in four directions with the increasing distance of 100, 300 and 500 m away from each brick kiln at all study sites. The concentration of the PAHs was determined through high-performance liquid chromatography (HPLC). The results of the current study report that all six PAH compounds were detected in the soil samples and the concentration of the studied PAHs varied with increasing distance from the source and with directions. Total PAHs (∑PAHs) concentration at study sites ranged from 2.74 to 4.51 µg/g and 1.05 to 1.13 µg/g in summer and winter seasons, respectively. The maximum concentrations of the PAHs were found in the summer as compared to the PAHs detected in winter. The soil was dominated by low molecular weight (LMW) PAH compounds in the summer whereas, in the winter soil was dominated by high molecular weight (HMW) PAH compounds. The concentration levels of all detected PAHs also varied among the studied sites. Carcinogenic potency of PAHs in studied samples was less than 1 except the soil samples from Mastung. No correlation was noticed between physiochemical properties and ∑PAHs. It is recommended that the soil near the brick kilns be regularly monitored for the presence of PAHs due to their high potential of carcinogenicity.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants that originate mainly from anthropogenic sources. PAHs have elicited much concern because they exhibit strong toxic, carcinogenic, and mutagenic properties. Agricultural soil is at risk of PAH contamination mainly caused by atmospheric depositions, wastewater irrigation, or organic substances and biowaste applied as fertilizers. The surface agricultural soils were collected from Shandong in July 2015, and measured for 16 US EPA priority PAHs using high performance liquid chromatography with UV and fluorescence detector. The content and composition of PAHs were analyzed. The differences of PAHs between soils from the field for growing crops and from vegetable greenhouses, and between soils from point sources and from non-point sources were compared. The sources of PAHs were determined with methods of ratio between PAHs and positive matrix factorization (PMF), and the risks of PAHs were assessed. The results showed that the total content of 16 PAHs (∑16PAHs) ranged from 111.5 ng·g-1 to 2744.1 ng·g-1, with the mean of 556.3 ng·g-1. The content of 3-ring PAHs was relatively high, with the mean of 201.5 ng·g-1; while the contents of 2-ring and 6-ring PAHs were relatively low, with the mean of 39.3 ng·g-1 and 43.4 ng·g-1, respectively. According to the contamination classification in Poland, 71% of the samples in Shangdong were weakly contaminated. Compared with other areas in China, the content of PAHs in the agricultural soils in Shandong was in the middle range. Acenaphthene, fluorine, and fluoranthene were the major PAH compounds, accounting for more than 10% of the total PAHs; while the contribution of indeno (1,2,3-cd) pyrene was low. The content of ∑16PAHs and contribution of 7 carcinogenic PAHs were significantly higher in soils polluted by point sources than those in soils from non-point sources. Moreover, the contribution of PAHs with 2-3 rings was significantly higher in soils from non-point sources, while the contribution of PAHs with 4-6 rings was significantly higher in soils polluted by point sources. There was no significant difference in soils from vegetable greenhouses and from adjacent field soils, and the contribution of PAHs with 3-4 rings was high. The PAH isomer pair ratios of Ant/(Ant+Phe), Flu/(Flu+Pyr), BaA/(BaA+Chr), and InP/(InP+BP) were utilized as molecular indices to elucidate the possible PAH sources, and the results suggested that the PAHs in the soils were mainly from combustion. To quantitatively assess the contribution of various sources to PAH contamination, PMF was used to analyze the sources. The sources of PAHs were combustion of coal biomass, oil combustion from traffic, coking, and petroleum pollution, with contribution of 42.7%, 19.3%, 22.8% and 15.2%, respectively. Toxic equivalency factors were used to evaluate PAH contamination in the soils, and the carcinogenicity of other PAHs relative to BaP was quantified to estimate the BaP-equivalent concentration (TEQBaP). The TEQBaPof 16 PAHs (∑16TEQBap) in soils from non-point sources and vegetable greenhouses was 31.69 and 44.47 ng·g-1, respectively, which were below the safe value in Canadian soil quality guidelines. However, the ∑16TEQBap in some field soils from point sources exceeded the safe value, indicating that there were potential risks in the soils from point sources in Shandong.

A focus on soil quality issues in the EU has resulted in extensive studies aimed to development of a Soil Framework Directive as well as of other new relevant regulations and standards, in parallel with setting up a harmonized European Soil Monitoring System for routine soil monitoring/ screening with use of reference analytical methods. Polycyclic Aromatic Hydrocarbons (PAHs) belong to the most problematic contaminants from the local sources and diffuse inputs to be monitored and controlled. This study presents the screening survey for 16 PAHs carried out in 2000 in the area severely impacted by the catastrophic flood of 1997 in the Odra River valley in Poland, which affected also Czech Republic and Germany. Within this survey, 16 PAH contents in soils due to river sediments deposition resulting from the flood, as well as the effect of flood on the distribution of PAHs in soils of the affected area were assessed (by the GC-MS reference methods) in view of soil quality standards and need for remediation. The postflood PAH spatial distribution with use of the Geographical Infor- mation System (GIS) showed distinct correlation with floodwater flow conditions, while total 16 PAH and specific compounds concentrations in the upper soil layer 0-0.20 m appeared to be mostly within the standard limits. In 17% of composite samples, 16 PAH concentrations were found to be considerably elevated, up to the values >1,000 �� g/kg, and exceeded the standards for agricultural soils in particular samples. PAH compounds displayed also different vertical migration potential in soils. The occurrence of the maximum PAH concentrations in the floodwater stagnation areas

Equilibrium partitioning behavior of naphthalene and phenanthrene with axenic microplantlets of the temperate green seaweed Acrosiphonia coalita

In this study, the degradation potential of five polycyclic aromatic hydrocarbons (PAHs) by aerobic mixed bacterial cultures was investigated. Microorganisms were isolated from hydrocarbon contaminated soils of Shadegan wetland located in southwest of Iran. The degradation experiments were conducted in liquid cultures. PAH or PAHs concentration was 100 mg/L at the beginning of degradation experiments. After ten days incubation, the mixed culture was capable of degrading phenanthrene completely and anthracene 80%, pyrene 60%, fluorene 30%, and fluoranthene 20%, individually. Optimal temperature and pH were as 30 °C and 7.0 respectively. Results showed that in samples containing a mixture of the five PAHs, fluoranthene could degrade cometabolically and the rate of degradation increased from 20 to 44%. It was observed also that PAHs degradation could be enhanced by the individual addition of yeast extract or glucose. The isolated mixed culture is valuable in bioremediation of PAH-contaminated environments.

The U.S. Geological Survey, in cooperation with the Tahoe Regional Planning Agency and the Lahontan Regional Water-Quality Control Board, sampled Lake Tahoe, major tributary streams to Lake Tahoe, and several other lakes in the Lake Tahoe Basin for manmade organic compounds during 1997-99. Gasoline components were found in all samples collected from Lake Tahoe during the summer boating season. Methyl tert-butyl ether (MTBE), benzene, toluene, ethylbenzene, and xylenes (BTEX) were the commonly detected compounds in these samples. Most samples from tributary streams and lakes with no motorized boating had no detectable concentrations of gasoline components. Motorized boating activity appears to be directly linked in space and time to the occurrence of these gasoline components. Other sources of gasoline components to Lake Tahoe, such as the atmosphere, surface runoff, and subsurface flow, are minor compared to the input by motorized boating. Water sampled from Lake Tahoe during mid-winter, when motorized boating activity is low, had no MTBE and only one sample had any detectable BTEX compounds. Soluble pesticides rarely were detected in water samples from the Lake Tahoe Basin. The only detectable concentrations of these compounds were in samples from Blackwood and Taylor Creeks collected during spring runoff. Concentrations found in these samples were low, in the 1 to 4 nanograms per liter range. Organochlorine compounds were detected in samples collected from semipermeable membrane devices (SPMD's) collected from Lake Tahoe, tributary streams, and Upper Angora Lake. In Lake Tahoe, SPMD samples collected offshore from urbanized areas contained the largest number and highest concentrations of organochlorine compounds. The most commonly detected organochlorine compounds were cis- and trans-chlordane, p, p'-DDE, and hexachlorobenzene. In tributary streams, SPMD samples collected during spring runoff generally had higher combined concentrations of organochlorine compounds than those collected during baseflow conditions. Upper Angora Lake had the fewest number of organochlorine compounds detected of all lake samples. Dioxins and furans were not detected in SPMD samples from two sites in Lake Tahoe or from two tributary streams. The number of polycyclic aromatic hydrocarbon (PAH) compounds and their combined concentrations generally were higher in samples from Lake Tahoe than those from tributary streams. Areas of high-motorized boating activity at Lake Tahoe had the largest number and highest concentrations of PAH's. PAH compounds were detected in samples from SPMD's in four of six tributary streams during spring runoff, all tributary streams during baseflow conditions, and at all lake sites. The most commonly detected PAH's in tributary streams during spring runoff were phenanthrene, fluoranthene, pyrene, and chrysene, and during baseflow conditions were phenanthrene, 1-methylphenanthrene, diethylnaphthalene, and pyrene. Upper Truckee River, which has an urban area in its drainage basin, had the largest number and highest combined concentration of PAH's of all stream samples. Bottom-sediment from Lake Tahoe had detectable concentrations of p-cresol, a phenol, in all but one sample. A sample collected near Chambers Lodge contained phenol at an estimated concentration of 4 micrograms per kilogram (?g/kg). Bottom-sediment samples from tributary streams had no detectable concentrations of organochlorine or PAH compounds. Several compounds were detected in bottom sediment from Upper Angora Lake at high concentrations. These compounds and their concentrations were p, p'-DDD (10 ?g/kg), p, p'-DDE (7.4 ?g/kg), 2,6-dimethylnaphthalene (estimated at 190 ?g/kg), pentachlorophenol (3,000 ?g/kg), and p-cresol (4,400 ?g/kg).

The 24-h records of polycyclic aromatic hydrocarbons (PAHs) concentrations in the particulate phase were obtained for the urban site (52.42°N, 16.88°E) in Poznan, one of the largest cities in central Poland, between January and December 2014. The main goal of this study was to identify major emission sources of PAHs congeners and factors controlling their seasonal variability. The most abundant in the particulate matter PAH compound was pyrene (mean concentration of 2.29 ± 4.68 ng m–3, maximum of 22.51 ng m–3), followed by benzo(a)pyrene, dibenz(ah)anthracene, benzo(k)fluoranthene, benzo(b)fluoranthene, phenanthrene, benzo(ghi)perylene, chrysene, benz(a)anthracene and fluoranthene. The results showed a sharp decrease in PAHs concentrations during summer measurements (photodecomposition, high precipitation frequency), and high levels of the quantified PAHs during cold study period (increase anthropogenic emission, low air temperature). During the cold season in 2014, predominant PAHs congeners were: pyrene (26.0%) and 5-ring PAH compounds such as benzo(a)pyrene (19.4%) > dibenz(ah)anthracene (13.7%) ≥ benzo(k)fluoranthene (13.3%) > benzo(b)fluoranthene (9.8%), mostly associated with mixed sources (i.e., combustion, wood burning, industrial emission, traffic emission), whereas during warm study period we observed a large contribution (> 20%) of pyrene, dibenz(ah)anthracene and benzo(a)pyrene in particulate matter. The summertime measurements showed that local emission from the traffic (i.e., diesel and gasoline exhausts) was the second important source of PAHs in aerosol. The coal combustion for residential heating and industrial usage were most pronounced PAHs sources during the entire study period. The multivariate statistical technique (Principal Component Analysis) combined with some diagnostic ratios were applied to provide detailed characteristics of sources and processes related to the polycyclic aromatic hydrocarbons in different seasons. The results from this study are in good agreement with most of the studies focused on seasonal variability of PAHs in the atmosphere.

To increase the biodegradation of phenanthrene (PHE), pyrene (PYR) and fluoranthene (FLU) through mixed cultures of polycyclic aromatic hydrocarbon (PAH)-degrading bacteria, using modified repeated batch fermentation. Novel bacterial strains of Pseudomonas putida, Pseudomonas sp. and Ralstonia eutropha were cultivated and the biodegradation and conversion of mixed PAH to medium-chain-length polyhydroxyalkanoates (MCL-PHA) was determined. The highest degradation of PAH (100%) and PHA production (50·0%) was obtained in medium containing 30mmoll-1 of mixed PAH after three cycles of repeated batch fermentation. The concentration of PAH in the reactor was increased from 30 to 90mmoll-1 with repeated additions of PAH, and bacteria were able to produce PHA at 40% of cell dry mass. The MCL-PHA were identified by gas chromatography/mass spectroscopy, with the 3-hydroxydecanoate (3-HD) monomer higher than 75mol.%. This study demonstrated that the biodegradation of PHE, PYR and FLU was enhanced by modified repeated batch fermentation using a mixed culture of bacteria. In addition, this fermentation strategy also increased the production of PHA, with an increase in monomer composition. This was the first study to describe the enhancement of the degradation of mixed solutions of PHE, PYR and FLU, and PHA production, using novel mixed bacterial cultures and modified repeated batch fermentation. The MCL-PHA formed had uniquely high 3-HD content.