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Three strains of novel bacteria were isolated from oil-contaminated sediment from the Arabian Gulf (Brevibacillus brevis T2C2008, Proteus mirabilis T2A12001, and Rhodococcus quinshengi TA13008). The isolated strains were tested for their degrading efficacy of low and high molecular hydrocarbon (naphthalene and pyrene). The efficacy of the two-hydrocarbon degradation by the isolates bacterial was determined at a temperature of 25 °C and 37 °C and pH of 5.0 and 9.0. In inoculated media at 37 °C, Rhodococcus qinshengi fully metabolized naphthalene and degrade 56% of pyrene. Brevibacillus brevis break down over 80% of naphthalene at room temperatures (25 °C). However, it was found that P. mirabilis and R. qinshengi biodegraded nearly 94% of naphthalene in the incubated media. The capacity for pyrene and naphthalene degradation in varying pH and temperature conditions was shown to be significant in Rhodococcus qinshengi because of its mineralization exceeding 50% across the tested pH and temperature. This implies that the isolated strains are ideal for biodegradation of contaminated sediment with naphthalene and pyrene. [ABSTRACT FROM AUTHOR]

Bacteria play an important role in the removal of polycyclic aromatic hydrocarbons (PAHs) from polluted environments. In marine environments, Cycloclasticus is one of the most prevalent PAH-degrading bacterial genera. However, little is known regarding the degradation mechanisms for multiple PAHs by Cycloclasticus. Cycloclasticus sp. strain P1 was isolated from deep-sea sediments and is known to degrade naphthalene, phenanthrene, pyrene, and other aromatic hydrocarbons. Here, six ring-hydroxylating dioxygenases (RHDs) were identified in the complete genome of Cycloclasticus sp. P1 and were confirmed to be involved in PAH degradation by enzymatic assays. Further, five gene clusters in its genome were identified to be responsible for PAH degradation. Degradation pathways for naphthalene, phenanthrene, and pyrene were elucidated in Cycloclasticus sp. P1 based on genomic and transcriptomic analysis and characterization of an interconnected metabolic network. The metabolic pathway overlaps in many steps in the degradation of pyrene, phenanthrene, and naphthalene, which were validated by the detection of metabolic intermediates in cultures. This study describes a pyrene degradation pathway for Cycloclasticus. Moreover, the study represents the integration of a PAH metabolic network that comprises pyrene, phenanthrene, and naphthalene degradation pathways. Taken together, these results provide a comprehensive investigation of PAH metabolism in Cycloclasticus. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Decreasing the cell viability by strong interaction and ROS generation. • Nano-SIMS could prove the contribution of hematite to intracellular iron, directly. • Restricting the BaP bioaccessibility to the bacterium. Abstract Iron oxides are reactive inorganic soil components that play an important role in the fate and transport of organic pollutants. Here, hematite was selected to investigate its effect on the biodegradation of benzo[a]pyrene (BaP) by Paracoccus sp. strain HPD-2. Approximately 60% of the total BaP was degraded in the absence of hematite after 7 days but only 30.8 and 20.8% of that was degraded after the addition of 10 and 20 mg mL–1 hematite, respectively, indicating that the addition of hematite could significantly inhibit the biodegradation of BaP (P < 0.05). The hematite also lowered bacterium activity by coating the cells and by generating reactive oxygen species that destroyed the cells. Two-photon confocal laser scanning microscope images showed that the addition of hematite substantially decreased the amount of BaP combined with the bacterium, and this also enabled us to observe directly the migration and regression of BaP in the interaction between HPD-2 and hematite. Higher death ratio of HPD-2 might lower the BaP access to live cells because dead cells have a higher adsorption affinity for BaP than live cells. These observations enhance our understanding of the mechanisms by which metal oxides, organic pollutants and degrading-bacteria interact during the biodegradation process. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants from incomplete combustion and petroleum products. As the molecular weight increases, PAHs become more recalcitrant to biodegradation. A bacterial strain capable of metabolizing the four fused aromatic ring PAH pyrene was isolated and characterized. The analysis of 16S rRNA gene revealed that it belongs to Achromobacter xylosoxidans species . A. xylosoxidans PY4 can utilize pyrene as the sole source of carbon. PY4 has a doubling time (dt) of less than 1 day when it grows in the presence of 1–5 mg l −1 pyrene, a dt range similar to that of the most efficient pyrene biodegrading bacteria described so far. The optimal pyrene degradation conditions are at pH 7–9, 37–40 °C, and 0–2.5% NaCl. PY4 also utilizes salicylic acid, catechol, naphthalene, anthracene and phenanthrene. PY4 degrades more than 50% of 100 mg l −1 of pyrene, within the first 15 days, at a rate of 0.069 day −1 , R 2  = 0.99. The metabolites include monohydroxypyrene, 1-methoxyl-2-H-benzo[h]chromene-2-carboxylic acid, 9,10-phenanthrenequinone, 1-methoxyl-trans-2′-carboxybenzalpyruvate, and dibutyl-phthalate. Up-expressed proteins in response to pyrene are involved in cell homeostasis, genetic information synthesis and storage, and chemical stress. Among these proteins are 4-hydroxyphenylpyruvate dioxygenase and homogentisate 1,2-dioxygenase, involved in the lower pyrene degradation pathway. [ABSTRACT FROM AUTHOR]

Identifying functional microorganisms involved in the degradation of high-molecular-mass polycyclic aromatic hydrocarbons (HMM-PAHs) in agricultural soil environments could assist in developing bioremediation strategies for soil PAH contamination. Active populations of HMM-PAH degraders in agricultural soils are currently poorly understood. In this study, we identified aerobic pyrene-degrading bacteria in agricultural and industrial soils by [13C]pyrene incubations followed by DNA stable-isotope probing and high-throughput sequencing. More than 80% of pyrene was degraded during an incubation time of 35 days in both soils, with slower mineralization rates observed in agricultural soil compared with industrial soil. Members of the Pseudonocardia genus, not previously implicated in pyrene degradation, were the dominant pyrene-degrading population in agricultural soil; their relative abundance increased by three orders of magnitude. In industrial soil, Arthrobacter sp. appeared as the major pyrene degraders, while Pseudonocardia was not detectable. Mycobacterium, a group of well-known pyrene degraders, was found to be active in pyrene degradation in both soils. These results highlight the role of uncultivated members of Pseudonocardia in natural PAH biodegradation processes and expand our understanding of the metabolic potential of uncultivated microorganisms for bioremediation applications in agricultural soils. [ABSTRACT FROM AUTHOR]

The bacterial community composition using a consortium (CON) with or without methyl-β-cyclodextrin (MCD), used to bioremediate the pyrene-contaminated soil was evaluated through stable-isotope probing (SIP). Microcosms were artificially contaminated with13C pyrene at 15 ppm, and bacterial community composition was determined over a 14-day period. After 14 days, only 29.1% of pyrene was degraded in control, while 90.6% of pyrene was degraded by the bacterial community with MCD, showing the best bioremediation rate of all treatments. After 14 days, PAH degraders became dominated byProteobacteria. SphingomonasandPseudomonaswere the predominant genera in all treatments, andPseudomonaswas the main degrader from the bacterial community. The bacterial community was little affected by MCD. The results indicated that the combination of the bacterial community with MCD can be used to bioremediate PAHs polluted soil. [ABSTRACT FROM PUBLISHER]

Pseudomonas monteilii PL5 (PL5) was newly isolated from soil sample and was identified by 16S rDNA sequence analysis. The strain PL5 had a high potential to degrade pyrene (PYR) in both liquid solution and soil and was able to degrade 51.8% of PYR at 25 °C and pH 7.0 condition within 10 days. At 25 °C, the ability of strain PL5 to degrade PYR at different pH values followed the following order pH 6.0 > pH 7.0 > pH 8.0 > pH 9.0. Degradation of total PYR was 56.5 and 51.8% after 10 days at pH 6.0 and 7.0 with PYR half-lives of 8.8 and 9.2 days, respectively. The ability of strain PL5 degraded PYR under different temperatures was 35 > 25 > 15 °C at pH 6.0. Among the tested soils contaminated by PYR, the best degradation of PYR by strain PL5 occurred in paddy soil where the degradation was 57.5% after 10 days, and the half-life of PYR was reduced 19-fold in the presence of strain PL5. This study suggested that P. monteilii PL5 could be used for the bioremediation of the contaminated soil and water through the degradation of PYR. [ABSTRACT FROM AUTHOR]

Plants and associated microbial communities can actively participate in the biodegradation of organic pollution. Potexperiments were conducted to explore the plant–microbe interrelations on Di-(2-ethylhexyl) phthalate (DEHP) and pyrene degradation in a soil culture system. Three dicotyledonous plant species, Ceylon spinach (Gynuracusimbua(D. Don) S.Moore), sunflower (Helianthus annuusL.), and Shuidong mustard (Brassica juncea(L.) Coss.var.foliosaBailey), were cultivated for 45 days in DEHP and pyrene co-contaminated soils using three initial content levels: 0 (T0), 20 (T20) and 50 mg kg−1(T50) with no plants (NP) as control. The results demonstrated that Shuidong mustard biomass and sunflower biomass had significantly positive correlations with the removal rate of DEHP (P < .05), respectively, while Ceylon spinach biomass has no significant correlation with the removal rate of DEHP. Shuidong mustard–actinomycetes and Ceylon spinach–actinomycetes accelerated the removal rate of pyrene, and sunflower–gram-positive bacteria could also enhance the removal rate of pyrene. Our results suggest that a better understanding of plant–microbe interrelations could be exploited to enhance the phytoremediation of organic co-contaminated soils. [ABSTRACT FROM AUTHOR]

Bioremediation use to promote degradation and/or removal of contaminants into nonhazardous or less-hazardous substances from the environment using microbial metabolic ability. Pseudomonas spp. is one of saprotrophic soil bacterium and can be used for biodegradation of polycyclic aromatic hydrocarbons (PAHs) but this activity in most species is weak. Phenanthrene and pyrene could associate with a risk of human cancer development in exposed individuals. The aim of the present study was application of genetically engineered P. putida that produce dioxygenase for degradation of phenanthrene and pyrene in spiked soil using high-performance liquid chromatography (HPLC) method. The nahH gene that encoded catechol 2,3-dioxygenase (C23O) was cloned into pUC18 and pUC18-nahH recombinant vector was generated and transformed into wild P. putida, successfully. The genetically modified and wild types of P. putida were inoculated in soil and pilot plan was prepared. Finally, degradation of phenanthrene and pyrene by this bacterium in spiked soil were evaluated using HPLC measurement technique. The results were showed elimination of these PAH compounds in spiked soil by engineered P. putida comparing to dishes containing natural soil with normal microbial flora and inoculated autoclaved soil by wild type of P. putida were statistically significant (p<0.05). Although adding N and P chemical nutrients on degradation ability of phenanthrene and pyrene by engineered P. putida in soil were not statistically significant (p>0.05) but it was few impact on this process (more than 2%). Additional and verification tests including catalase, oxidase and PCR on isolated bacteria from spiked soil were indicated that engineered P. putida was alive and functional as well as it can affect on phenanthrene and pyrene degradation via nahH gene producing. These findings indicated that genetically engineered P. putida generated in this work via producing C23O enzyme can useful and practical for biodegradation of phenanthrene and pyrene as well as petroleum compounds in polluted environments. [ABSTRACT FROM AUTHOR]

High molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) are more persistent and less bioavailable because of their poorer solubility in saline environments. In this study, a new halophilic bacterium capable of degrading various HMW-PAHs was isolated from the coastal soil of Yellow Sea, China. It was identified as Thalassospira sp. strain TSL5-1 based on 16S rRNA gene sequence analysis and biochemical tests. Influences of salinity, pH and additional nutrients on pyrene degradation by TSL5-1 were investigated. The pyrene degradation could occur at salinity ranging from 0.5% to 19.5%, with optimal value kept between 3.5% and 5%. The degradation activity was affected greatly by pH fluctuation. Yeast could efficiently promote pyrene removal while peptone had the opposite effect. GC–MS analysis revealed that the pyrene was degraded to generate a series of intermediates such as phenanthrene-4-carboxylic acid methyl ester, 2-hydroxy-2-H-benzo[h]chromene-2-carboxylic acid, 2-carboxylbenzaldehyde, phthalic acid and salicylic acid. Particularly, identification of phthalic acid and salicylic acid showed that phthalate and salicylic acid routes were simultaneously contained in the pyrene degradation, which was remarkably different from those for other pyrene-degraders. To our knowledge, it was the first time to propose a metabolic pathway of pyrene degradation by Thalassospira strains. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAH) are toxic pollutants widely distributed in the environment due to natural and anthropogenic processes. In order to mitigate tar oil contaminations with PAH, research on improving bioremediation approaches, which are sometimes inefficient, is needed. However, the knowledge on the fate of PAH-derived carbon and the microbial degraders in particular in compost-supplemented soils is still limited. Here we show the PAH carbon turnover mass balance in microcosms with soil-compost mixtures or in farmyard fertilized soil using [C]-pyrene as a model PAH. Complete pyrene degradation of 100 mg/kg of soil was observed in all supplemented microcosms within 3 to 5 months, and the residual C was mainly found as carbon converted to microbial biomass. Long-term fertilization of soil with farmyard manure resulted in pyrene removal efficiency similar to compost addition, although with a much longer lag phase, higher mineralization, and lower carbon incorporation into the biomass. Organic amendments either as long-term manure fertilization or as compost amendment thus play a key role in increasing the PAH-degrading potential of the soil microbial community. Phospholipid fatty acid stable isotope probing (PLFA-SIP) was used to trace the carbon within the microbial population and the amount of biomass formed from pyrene degradation. The results demonstrate that complex microbial degrader consortia rather than the expected single key players are responsible for PAH degradation in organic-amended soil. [ABSTRACT FROM AUTHOR]

This investigation evaluates the contrasting metabolic characteristics of anthracene and pyrene by wood rot fungus Pycnoporus sanguineus H1. Under in vivo conditions, P. sanguineus H1 degraded 67.5% of the anthracene and showed maximal laccase activity of 1568.2 U L −1 . When piperonyl butoxide (PB) was added to the liquid cultures, the anthracene degradation rate increased to 73.1% and maximal laccase activity increased to 2034.3 U L −1 . For pyrene, the degradation rate was 31.1%; however, after PB addition, the value decreased to 5.3% while maximal laccase activity increased to 1625.3 U L −1 from 1469.1 U L −1 . Under in vitro conditions, the extracellular liquid culture (10 kDa membrane, ultra-filtered) transformed 59.9% of the anthracene, while addition of 2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) enhanced the anthracene transformation rate up to 92.0%. The extracellular liquid did not convert the pyrene, however, suggesting that anthracene is modified extracellularly, (likely via laccase) while pyrene is not. Whole mycelium, as well as homogenized mycelium and microsomal proteins, transformed both anthracene and pyrene; conversion was inhibited to some extent by the PB, implying that cytochrome P450 participates in intracellular PAHs transformation. Additional evidence that ABTS enhances anthracene transformation by homogenized mycelium suggests that mycelium-associated laccase cooperates in the intracellular degradation of anthracene. These results altogether elucidate the metabolism of PAHs by P. sanguineus via extracellular laccase, intracellular cytochrome P450, and mycelium-associated laccase. [ABSTRACT FROM AUTHOR]

Environmental contamination by polycyclic aromatic hydrocarbons ( PAHs) typically occurs as mixtures of compounds. In this study, the response of indigenous soil bacterial and fungal communities to mixtures containing phenanthrene, fluoranthene and benzo( a)pyrene in various combinations was examined using molecular fingerprinting techniques and quantification of a key PAH degradative gene. Results were compared to a parallel study by Sawulski et al. (2014) which examined the effect of these PAHs on soil microbial communities when added as single contaminants. The rate of degradation of individual PAHs varied depending on whether the PAH was present as a single contaminant or in a mixture; phenanthrene was degraded most rapidly when present as a sole contaminant, fluoranthene was removed faster in the presence of the lower molecular weight phenanthrene and the rate of benzo( a)pyrene degradation was reduced in the presence of the 4-ring PAH, fluoranthene. Bacterial and fungal assemblages differed significantly between treatments regardless of which PAH was added to soil. Although less abundant than the Gram-negative PAH- RHDα gene, the gene associated with Gram-positive bacteria responded to a greater extent to the presence of PAHs, either as single compounds or as mixtures and this increase was significantly correlated with PAH degradation. Significance and Impact of the Study Contaminated sites generally contain complex mixtures of pollutants. Development of effective bioremediation strategies for contaminated soils requires knowledge of the response of soil microbial communities to such mixtures. This study provides information on the degradation of different mixtures of three priority pollutants in soil with a history of polycyclic aromatic hydrocarbon contamination and examines the response of soil bacterial and fungal communities to the presence of these pollutants as sole contaminants or as part of a mixture. This is one of few studies to-date to compare the effects of single compounds and pollutant mixtures on more than one soil microbial community. [ABSTRACT FROM AUTHOR]

The benzo[a]pyrene accumulation and migration regularities in chernozemic soils under the aerotechnogenic emission zone were revealed on the basis of long-term monitoring researches. A new method of subcritical water extraction has been developed for determination of benzo[a]pyrene from soils of the emissions zone of Novocherkassk Power Station one of the largest thermal power enterprises in Russian Federation. It is shown that the soils adjacent to a source of emission are polluted by benzo[a]pyrene at distance to 5 km. Trends in the accumulation of benzo[a]pyrene in soil zones of the thermal power plant influence have been researched over a 5-year period of monitoring observations. The assessment of soils pollution extent by benzo[a]pyrene is given. [ABSTRACT FROM AUTHOR]

The main aim of this study was to investigate the effect of a rhamnolipid biosurfactant on biodegradation of 14C labeled phenanthrene and pyrene under desorption-limiting conditions. The rhamnolipid caused a significant solubilization and enhanced biodegradation of PAHs sorbed to soils. The enhancement was, however, negatively influenced by experimental conditions that caused an enrichment of slow desorption fractions. These conditions included aging, a higher organic matter content in soil, and previous extraction with Tenax to remove the labile-desorbing chemical. The decline in bioavailability caused by aging on sorbed 14C-pyrene was partially reversed by rhamnolipids, which enhanced mineralization of the aged compound, although not so efficiently like with the unaged chemical. This loss in biosurfactant efficiency in promoting biodegradation can be explained by intra-aggregate diffusion of the pollutant during aging. We suggest that rhamnolipid can enhance biodegradation of soil-sorbed PAHs by micellar solubilization, which increase the cell exposure to the chemicals in the aqueous phase, and partitioning into soil organic matter, thus enhancing the kinetics of slow desorption. Our study show that rhamnolipid can constitute a valid alternative to chemical surfactants in promoting the biodegradation of slow desorption PAHs, which constitutes a major bottleneck in bioremediation. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel Shewanella expression system for goldfish CYP1A was established. [•] High-level production of functional CYP1A was obtained. [•] Degradation of benzo[a]pyrene was observed by periplasmic fractions. [ABSTRACT FROM AUTHOR]

The enhancement of the degradation of polycyclic aromatic hydrocarbons (PAHs), exemplified by pyrene and phenanthrene, using mild grinding in the presence of common minerals was investigated. Magnetite, birnessite, and Na- and Cu-montmorillonite samples were loaded with pyrene or phenanthrene and ground manually or in a ball mill for short periods of time. The ground samples were analyzed for PAHs and for their metabolites, using high-performance liquid chromatography and liquid chromatography-mass spectrometry. No degradation of pyrene occurred when it was in contact with Na-montmorillonite or birnessite. Sorption of pyrene on Cu-montmorillonite enhanced its degradation, but grinding of the loaded clay actually inhibited pyrene's degradation. Phenanthrene hardly degraded on Cu-montmorillonite. Grinding magnetite loaded with either PAH resulted in a significant degradation of both (∼50% after grinding for 5 min), while in the nonground samples, negligible degradation was detected. The extent of degradation increased with the duration of grinding. The degradation of either PAH loaded on magnetite yielded oxidized products. In soil samples contaminated with PAHs and mixed with magnetite, a similar grinding-induced degradation pattern was observed, but with a lower rate. A liquid phase was required to initiate degradation in the soil. The liquid phase apparently served as the medium through which the pollutants reached the surface of the degradation-enhancing mineral. [ABSTRACT FROM AUTHOR]

Abstract: A Pseudomonas isolate, designated PAHAs-1, was found capable of reducing arsenate and degrading polycyclic aromatic hydrocarbons (PAHs) independently and simultaneously. This isolate completely reduced 1.5 mM arsenate within 48 h and removed approximately 100% and 50% of 60 mg l−1 phenanthrene and 20 mg l−1 pyrene within 60 h, respectively. Using PAHs as the sole carbon source, however, this isolate showed a slow arsenate reduction rate (4.62 μM h−1). The presence of arsenic affected cell growth and concurrent PAHs removal, depending on PAH species and arsenic concentration. Adding sodium lactate to the medium greatly enhanced the arsenate reduction and pyrene metabolism. The presence of the alpha subunit of the aromatic ring-hydroxylating dioxygenase (ARHD) gene, arsenate reductase (arsC) and arsenite transporter (ACR3(2)) genes supported the dual function of the isolate. The finding of latter two genes indicated that PAHAs-1 possibly reduced arsenate via the known detoxification mechanism. Preliminary data from hydroponic experiment showed that PAHAs-1 degraded the majority of phenanthrene (>60%) and enhanced arsenic uptake by Pteris vittata L. (from 246.7 to 1187.4 mg kg−1 As in the fronds). The versatile isolate PAHAs-1 may have potentials in improving the bioremediation of PAHs and arsenic co-contamination using the plant-microbe integrated strategy. [Copyright &y& Elsevier]

Highlights: [•] Surfactant-induced sorption was the primary contribution in pyrene biodegradation. [•] Highly positive correlation between B s ∗/B 0 ∗ and K d,s ∗/K d,0 ∗ was found. [•] Alteration of CSH and sorption ability of pyrene depended on surfactants structure. [ABSTRACT FROM AUTHOR]

Highlights: [•] Pseudomonas sp. Jpyr-1 could use pyrene as the sole carbon source. [•] Strain Jpyr-1 showed a very high degradation rate of pyrene. [•] Existence of the second PAH influenced pyrene degradation at different levels. [•] Metabolic route of Jpyr-1 to degrade pyrene was through the o-phthalate pathway. [ABSTRACT FROM AUTHOR]

Abstract: Benzo[a]pyrene (BaP) biodegradation by Stenotrophomonas maltophilia was studied under the influence of co-existed Cu(II) ions. About 45% degradation was achieved within 3d when dealing with 1mgL−1 BaP under initial natural pH at 30°C; degradation reached 48% in 2d at 35°C. Efficacy of BaP biodegradation reached the highest point at pH 4. In the presence of 10mgL−1 Cu(II) ions, the BaP removal ratio was 45% on 7th day, and maintained stable from 7 to 14d at 30°C under natural pH. The favorable temperature and pH for BaP removal was 25°C and 6.0 respectively, when Cu(II) ions coexisted in the solutions. Experiments on cometabolism indicated that S. maltophilia performed best when sucrose was used as an additional carbon source. GC–MS analysis revealed that the five rings of BaP opened, producing compounds with one or two rings which were more bioavailable. [Copyright &y& Elsevier]

Abstract: Polycyclic aromatic hydrocarbons (PAH) are ubiquitous pollutants that are toxic and recalcitrant to degradation by bacteria. This research evaluated the toxicity of different concentrations [10, 20, 40, 60, 80 and 100μgmL−1] of phenanthrene (PHE) or benzo[a]pyrene (BaP) on the growth of Rhizobium tropici CIAT899 under in vitro conditions as well as the potential degradation of PHE and BaP by this bacterium. At 24h, a 40% decrease in Rhizobium growth was observed when exposed to 40μgmL−1 of either PHE or BaP. Furthermore, bacterial growth was completely inhibited by PHE or BaP applied in 80 and 100μgmL−1. After 96h, the growth of R. tropici at 40μg PHEmL−1 or 60μg BaPmL−1 was similar to those treatments without PAH. To evaluate R. tropici degrading capabilities, supernatants of cultures with 40μg PHEmL−1 or 60μg BaPmL−1 were analyzed by gas chromatography coupled to mass spectrophotometer (GC–MS). R. tropici was able to degrade either PHE or BaP diminishing its concentration in 20% and 25% during the first 24h, degradation obtained at 120h was 50% and 45% for PHE or BaP, respectively. This research shows for the first time that R. tropici CIAT 899 grows in liquid culture medium contaminated with PAH, and moreover is able to growth and to degrade either PHE or BaP. [Copyright &y& Elsevier]

A pyrene-degrading consortium was enriched from sludge of coking wastewater treatment plant which included a combination of aerobic and anaerobic reactors. Biodegradation of pyrene by the consortium follows first-order kinetics. Addition of a co-substrate (glucose or anthraquinone) facilitated pyrene degrading. The highest degradation rate was achieved at 35°C and pH 7.0, as glucose was added. In this case, pyrene (100 mg L−1) was degraded by 93.1 % within 36 h. An intermediate, 1-naphthol was detected via GC-MS analysis, indicating that pyrene degradation by the consortium proceeded with a pathway different from that associated with Mycobacterium sp. By comparisons of 16S rRNA gene sequences, two strains in this consortium were identified as Pseudomonas sp. and Burkholderia sp. The enriched pyrene-degrading consortium from coking wastewater treatment system shows highest pyrene-degrading activity compared with the reported pyrene degraders. [ABSTRACT FROM AUTHOR]

A white-rot fungus of Polyporus sp. S133 was isolated from an oil-polluted soil. The metabolism of pyrene by this fungus was investigated in liquid medium with 5 mg of the compound. Depletion of pyrene was evident during the 30-day growth period and was 21% and 90%, respectively, in cometabolism and metabolism of pyrene alone. Pyrene was absorbed to fungal cells or biodegraded to form simpler structural compounds. Seventy-one percent of eliminated pyrene was transformed by Polyporus sp. S133 into other compounds, whereas only 18% was absorbed in the fungal cell. The effects of pH and temperature on biomass production of Polyporus sp. S133 for pyrene were examined; the properties of laccase and 1,2-dioxygenase produced by Polyporus sp. S133 during pyrene degradation were investigated. The optimal values of pH were 3, 5, and 4 for laccase, 1,2-dioxygenase, and biomass production, respectively, whereas the optimal values of temperature were 25 °C for laccase and 50 °C for 1,2-dioxygenase and biomass production. Under optimal conditions, pyrene was mainly metabolized to 1-hydroxypyrene and gentisic acid. The structure of 1-hydroxypyrene and gentisic acid was determined by gas chromatography-mass spectrometry after identification using thin-layer chromatography. [ABSTRACT FROM AUTHOR]

Abstract: The effect of ryegrass (Lolium perenne L.) root-exudates concentration on pyrene degradation and the microbial ecological characteristics in the pyrene contaminated soil was investigated by simulating a gradually reducing concentration of root exudates with the distance away from root surface in the rhizosphere. Results showed that, after the root-exudates were added 15d, the pyrene residue in contaminated soil responded nonlinearly in the soils with the same pyrene contaminated level as the added root-exudates concentration increased, which decreased first and increased latter with the increase of the added root-exudates concentration. The lowest pyrene concentration appeared when the root exudates concentration of 32.75mgkg−1 total organic carbon (TOC) was added. At the same time, changes of microbial biomass carbon (MBC, Cmic) and microbial quotient (Cmic/Corg) were opposite to the trend of pyrene degradation as the added root-exudates concentration increased. Phospholipid fatty acid (PLFA) analysis revealed that bacteria was the dominating microbial community in pyrene contaminated soil, and the changing trends of pyrene degradation and bacteria number were the same. The changing trend of endoenzyme-dehydrogenase activity was in accordance with that of soil microbe, indicating which could reflect the quantitative characteristic of detoxification to pyrene by soil microbe. The changes in the soils microbial community and corresponding microbial biochemistry characteristics were the ecological mechanism influencing pyrene degradation with increasing concentration of the added root-exudates in the pyrene contaminated soil. [Copyright &y& Elsevier]

Abstract: A laboratory study was conducted to assess the feasibility of a washing process with nonionic surfactant in combination with EDDS for the simultaneous mobilization of MTEs and PAH compounds from a field-contaminated soil. Unit processes consisting of complexometric extraction and surfactant-assisted mobilization were combined with reagent regeneration and detoxification steps to generate innocuous products. Thirty minutes of ultrasonic mixing of the soil with a combination of 20mLL−1 surfactant suspension and a sparing quantity (2mmol) of EDDS mobilized virtually all of the benzo[α] pyrene (B(a)P) and chrysene (Cry) and an appreciable portion of the burdens of Cd, Cr, Mn, Ni, Pb and Zn, lesser amounts of the As and Cu, but only small quantities of Al and Fe. Relative to individual reagents, combinations of surfactant (Brij98), with EDDS increased the recovery of B(a)P but seemingly did not influence Cry extraction efficiencies perceptibly. Nine sequential washes with the same initial dosage of mobilization aids decreased the quantities of both PAHs to levels in the soil that conformed to recommended maxima. What resulted was a soil that had been cleaned and a limited quantity of innocuous wash water. [Copyright &y& Elsevier]

Mycobacterium sp. strain KMS utilizes pyrene, a high-molecular weight polycyclic aromatic hydrocarbon (PAH), as a sole carbon source. Bioinformatic analysis of the genome of isolate KMS predicted 25 genes with the potential to encode 17 pyrene-induced proteins identified by proteomics; these genes were clustered on both the chromosome and a circular plasmid. RT-PCR analysis of total RNA isolated from KMS cells grown with or without pyrene showed that the presence of pyrene increased the transcript accumulation of 20 of the predicted chromosome- and plasmid-located genes encoding pyrene-induced proteins. The transcribed genes from both the chromosome and a circular plasmid were within larger regions containing genes required for PAH degradation constituting PAH-degrading gene islands. Genes encoding integrases and transposases were found within and outside the PAH-degrading gene islands. The lower GC content of the genes within the gene island (61%-64%) compared with the average genome content (68%) suggested that these mycobacteria initially acquired these genes by horizontal gene transfer. Synteny was detected for the PAH-degrading islands in the genomes of two additional Mycobacterium isolates from the same PAH-polluted site and of two other pyrene-degrading Mycobacterium from different sites in the United States of America. Consequently, the gene islands have been conserved from a common ancestral strain. [ABSTRACT FROM AUTHOR]

Two-proton or two-electron transfer of the title biphenolic dication proceeds nearly simultaneously to induce 2,6′/2′,6- or 6,6′-bond formation to give dioxapyrene or dihydrophenanthrene derivatives, respectively, with vivid changes in color (halochromism and electrochromism). [ABSTRACT FROM AUTHOR]

This study investigated the interaction of the macrophyte Acorus calamus and sediment microbial fuel cells (SMFC) during the degradation of high molecular weight-polycyclic aromatic hydrocarbons (HMW-PAHs) in sediments. Over 367-days, the combination of macrophyte and SMFC led to an increase in pyrene and benzo[a]pyrene degradation rates by at least 70% compared to SMFC or macrophyte alone. While either the macrophyte or SMFC increased redox potential in sediments, redox potentials near the anode (approximately 6 cm depth) in the macrophyte-SMFC combination were markedly lower than that in the only macrophyte treatment. Moreover, rhizospheric bacterial communities in macrophyte-SMFC and macrophyte treatments were distinctly different. Aerobic genera (Vogesella, Pseudomonas, Flavobacterium and Rhizobium) and anaerobic genera (Longilinea, Bellilinea, Desulfobacca and Anaeromyxobacter) became dominant in the rhizosphere in macrophyte and macrophyte-SMFC treatments, respectively. In addition, the macrophyte-SMFC combination improved the numbers of not only aerobic but anaerobic PAHs degraders in sediments. So, the SMFC employment facilitated the formation of anoxic zones in sediments with oxygen loss and exudates from the roots. As a result, cooperation of anaerobic/aerobic microbial metabolism for accelerating HMW-PAHs removal occurred within sediments after combining macrophytes with SMFC. [ABSTRACT FROM AUTHOR]