Multilayered Vesicles Formed by Polyaromatic Oligoamines: Potential Light-Harvesting Spheres

This paper presents removal of some polycyclic aromatic hydrocarbons (PAHs) by silver nanoparticles (AgNPs) which were synthesised by garlic based green route method. Allivum sativum (Garlic) extract was used for the synthesis of silver nanoparticles Ag(P) as a green route process while synthetic chemical method was adopted for preparation of silver nanoparticles Ag(W). The synthesis of AgNPs was studied as a function of variation in volume of garlic extract, temperature and time. Solution of pyrene, anthracene and phenanthrene was prepared in n-hexane, and their removal efficiencies were studied. PAHs were removed successfully with optimal efficiency of more than 80% with the affinity order of removal, which followed Phenanthrene > Pyrene > Anthracene. The adsorption of PAHs on AgNPs is attributed to the occurrence of hydrophobic interactions. Ag (P) nanoparticles synthesized were found relatively better adsorbent than Ag (W), for removal of PAHs. It may be ascribed owing to the presence of more functional groups in the garlic extract participating in binding of PAH to the surface. The adsorption property of the AgNPs synthesized by both ways was studied and comparative results were obtained based on adsorption efficiency of PAHs. Further, FTIR and XRD were used to characterize the properties of garlic extract with binding and interaction taking place between AgNPs and PAHs. UV-Vis confirmed the formation of Ag(P) and Ag(W) by biological method and chemical wet co-precipitation method, respectively. Ag(P)can be applied over a wide range of temperature, due to stability of compounds present in Allivum sativum at high temperatures.

Determination of polycyclic aromatic hydrocarbons in urine of coke oven workers by headspace solid phase microextraction and gas chromatography–mass spectrometry

Although exposure to polycyclic aromatic hydrocarbons (PAHs) is common in both environmental and occupational settings, few studies have compared PAH exposure among people with different professions. The purpose of this study was to investigate the variations in recent PAH exposure among different occupational groups over time using national representative samples. The study population consisted of 4162 participants from the 2001 to 2008 National Health and Nutrition Examination Survey, who had both urinary PAH metabolites and occupational information. Four corresponding monohydroxy-PAH urine metabolites: naphthalene (NAP), fluorene (FLUO), phenanthrene (PHEN), and pyrene (PYR) among seven broad occupational groups were analyzed using weighted linear regression models, adjusting for creatinine levels, sociodemographic factors, smoking status, and sampling season. The overall geometric mean concentrations of NAP, FLUO, PHEN, and PYR were 6927, 477, 335, and 87 ng/L, respectively. All four PAH metabolites were elevated in the "extractive, construction, and repair (ECR)" group, with 21-42 % higher concentrations than those in the reference group of "management." Similar trends were seen in the "operators, fabricators, and laborers (OFL)" group for FLUO, PHEN, and PYR. In addition, both "service" and "support" groups had elevated FLUO. Significant (p < 0.001) upward temporal trends were seen in NAP and PYR, with an approximately 6-17 % annual increase, and FLUO and PHEN remained relatively stable. Race and socioeconomic status show independent effects on PAH exposure. Heterogeneous distributions of urinary PAH metabolites among people with different job categories exist at the population level. The upward temporal trends in NAP and PYR warrant reduction in PAH exposure, especially among those with OFL and ECR occupations.

Hydrocarbon pollution is a perennial problem not only in India but throughout the globe. A plethora of microorganisms have been reported to be efficient degraders of these recalcitrant pollutants. In the present study the Basidiomycetous a fungal isolate Agaricomycetes sp. AGAT was isolated from wood bark collected from Anand, Gujarat India. The isolate was screened for production of ligninolytic enzyme by primary and secondary screening. The isolate Agaricomycetes sp. AGAT is also able to degrade the polycyclic aromatic hydrocarbons (PAHs) present in the contaminated soil. The basidiomycetous fungal Agaricomycetes sp. AGAT was able to grow on 100 ppm Pyrene, Phenanthrene, Fluorene and Fluoranthene as a sole source of carbon in minimal medium. Maximum degradation of 78.53%, 85.05%, 20.5% and 70.49% of Phenanthrene, Pyrene, Fluoranthene and Fluorene respectively. The depletion in the residual PAHs in the culture medium was determined by HPLC. By GC-MS analysis metabolites were identified as 1-hydroxypyrene and phthalic acid from Pyrene, 9H- Fluoren-9-ol from Fluorene, Fluorene, 4-[1,2-dihydroxethyl] from Fluoranthene and 9,10-dihydro-9,10-dihydroxyphenanthrene from Phenanthrene. Further effect of surfactants, mediator were also studied. Phytotoxicity study of degraded metabolite was also studied.

The self-assembly of 3,6-disubstituted amine-linked phenanthrene trimers with a positively charged backbone leads to the formation of vesicles in aqueous medium. Previously, it was shown that 1,6-disubstituted phosphodiester-linked pyrene trimers - possessing a negatively charged backbone - assemble into sheets. Due to electrostatic interactions of the cationic and anionic species, alternated layering of the self-assembled structures is possible. The supramolecular polymers are usually preformed in their specific environment, in order to avoid problems because of different ambient conditions. Therefore, the layering on a mica substrate is done in a stepwise procedure. The structures formed by layer-by-layer self-assembly are analyzed by microscopy.

The solubilization of phenanthrene (PHE) and pyrene (PYR) by rhamnolipid biosurfactant was systematically investigated. The solubilities of both polycyclic aromatic hydrocarbons (PAHs) were increased linearly with the biosurfactant concentration at above critical micelle concentration. A competitive effect was observed between PHE and PYR. The solubility of PHE in a mixed system was lower than that in a single PAH system, whereas the solubility of PYR in a mixed system was enhanced. This is because the hydrophobicity of PYR is higher than that of PHE, so PYR is favored in the competitive solubilization. The combined effect of biosurfactant and dissolved organic matter (DOM) on PAH solubilization was also examined. Two kinds of DOM (derived from soil and from compost) were used. There was an obvious enhancement of solubility for PHE and PYR in systems with concurrence of DOM and biosurfacrant compared with systems with only DOM or biosurfactant; however, the enhancement in the mixed system was less than their additive. This could be explained as the formation of a DOM-biosurfactant complex. In addition, the solubility enhancement of PAHs in a compost-DOM system was higher than that in a soil-DOM system. This could be explained as functional group differences of two DOM types.

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.

Presence, distribution and risk assessment of polycyclic aromatic hydrocarbons in rice-wheat continuous cropping soils close to five industrial parks of Suzhou, China

Fil: Arias, Andres Hugo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Bahia Blanca. Instituto Argentino de Oceanografia. Universidad Nacional del Sur. Instituto Argentino de Oceanografia; Argentina. Universidad Nacional del Sur; Argentina

Polycyclic aromatic hydrocarbons (PAHs) pose risks to human and animal health, and their accumulation in crops is a concern for the food chain in the environment. Nanoparticles (NPs) have shown potential for chemical delivery and can be used to enhance plant resistance to PAHs. In this study, carotenoid-coated chitosan nanoparticles (CCNPs) loaded with β-carotene were prepared and applied to spinach grown in PAH-contaminated soil. The size of the CCNPs varied based on reaction conditions with temperature, TPP, and pH, with sizes ranging from 260 to 682 nm. After four weeks of treatment, the spinach showed varying growth responses depending on the specific CCNP treatment. The treatment with CCNPs prepared at 20 °C, pH 6, and 10 mg/mL TPP resulted in the best spinach growth, while the treatment at 40 °C, pH 6, and a TPP concentration of 20 mg/mL hindered growth; and the growth ration increased by over 47.4% compared to the normal growing spinach, the final biomass reached 2.53 g per plant. In addition, phenanthrene (PHE) and pyrene (PYR) predominantly accumulated more in the spinach roots, with variations depending on the specific CCNP treatment. The exogenous application of CCNPs can reduce the PAH transfer to the shoots. The bioconcentration factors and transfer factors of PYR and PHE reduced differential movement within the spinach plants, and the spinach prefers PYR to PHE in biological accumulation. This study offers a new understanding of the mechanisms underlying NPs and PAHs interactions and NP’s implications for crop protection and food safety.

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.

This paper presented the problem of information redundance factor in spectral data analysis. Three-component mixtures fluorescence spectra data of anthracene, pyrene and phenanthrene, which were typical polycyclic aromatic hydrocarbons (PAHs), were investigated through principal component regression analysis and move windows wavelength selection in chemometrics. Theoretical analysis and experimental result demonstrated that there was information redundancy in fluorescence signal; the data which have been optimized by redundancy techniques could show more realistic information of the test samples quantitatively, and for the multi-component mixed system with spectral overlapped seriously, analysis with the data which have been optimized through redundancy techniques could improve the sensitivity and stability of the models.

Despite keen interest in the development of efficient materials for the removal of polycyclic aromatic hydrocarbons (PAHs) in wastewater, the application of advanced composite materials is still unexplored and needs attention. Therefore, this study focused on the synthesis of the composite of oil palm leaves’ waste activated-carbon (OPLAC) and nano zerovalent iron (NZVI) at Fe:OPLAC = 1:1 (N-OPLAC-1) and 1:2 (N-OPLAC-2). The composite with enhanced surface properties was applied for removal of three PAHs including naphthalene (NAP), fluorene (FLU) and phenanthrene (PHE) in wastewater at various pH, dosages, contact time and initial concentration in batch testing. The PAHs’ removal parameters were optimized using design expert software. The PAHs’ removal efficiency was evaluated in produced water at optimized parameters. The results showed that the N-OPLAC-2 had superior surface properties compared to N-OPLAC-1. The removal of NAP, FLU and PHE was heterogenous, favorable and involved chemisorption proved by Freundlich isotherm and pseudo-second-order kinetic models using N-OPLAC-2. The optimum parameters were as follows: pH of 3, dosage and contact time of 122 mg/L and 49 min, respectively. The application of N-OPLAC-2 in produced water was favorable for removal of NAP, FLU and PHE and showed up to 90% removal efficiency, and higher stability up to 3 cycles. It can be concluded that the NZVI-OPLAC composite was successfully synthesized in this study and the materials showed good removal efficiency for three PAHs (NAP, FLU and PHE) in wastewater.

A comprehensive feasibility study of effectiveness and environmental impact of PAH bioremediation using an indigenous microbial degrader consortium and a novel strain Stenotrophomonas maltophilia CPHE1 isolated from an industrial polluted soil

Phenanthrene (PHEN), a polycyclic aromatic hydrocarbon (PAH), is degraded by white-rot fungi like Phanerochaete chrysosporium (the fungus has been renamed as Phanerodontia chrysosporium). PHEN is metabolized by P. chrysosporium and transformed into various monohydroxylated and dihydroxylated products. These intermediates are further degraded by cleavage of the aromatic ring. However, the enzymes involved in PHEN conversion in P. chrysosporium remain largely unidentified. We aimed to identify and characterize the P. chrysosporium enzymes involved in the degradation of PHEN and its intermediates. Recombinant P. chrysosporium flavoprotein monooxygenase 11 (FPMO11), a homolog of the salicylate 1-monooxygenase from the naphthalene-degrading bacterium Pseudomonas putida G7, was overexpressed in Escherichia coli. FPMO11 catalyzes the oxidative decarboxylation of 1-hydroxy-2-naphthoate (1H2N) and 2-hydroxy-1-naphthoate (2H1N) to 1,2-dihydroxynaphthalene (1,2DHN). To the best of our knowledge, this is the first study to identify and characterize enzymes with 1H2N and 2H1N monooxygenase activities in members of the FPMO superfamily. Additionally, our search for a dioxygenase with the ability to catalyze the aromatic ring cleavage of 1,2DHN led to the identification of intradiol dioxygenase (IDD) 1 and IDD2 from P. chrysosporium, which catalyzes the ring cleavage of 1,2DHN. Thus, this study also identified, for the first time, intradiol 1,2DHN dioxygenase activity in members of the IDD superfamily. The findings highlight the unique substrate spectra of FPMO11 and IDDs, rendering them attractive candidates for biotechnological applications, especially mitigation of environmental and health risks associated with PAH pollution.IMPORTANCEPhenanthrene (PHEN), a polycyclic aromatic hydrocarbon (PAH), is a widely studied pollutant in environmental science and toxicology due to its presence in fossil fuels, tobacco smoke, and as a byproduct of incomplete combustion processes. White-rot fungi like P. chrysosporium can degrade PHEN through the production of extracellular oxidative enzymes. We investigated the properties of PHEN-degrading enzymes in P. chrysosporium, specifically one flavoprotein monooxygenase (FPMO11) and two intradiol dioxygenases (IDD1 and IDD2). Our findings indicate that the enzymes catalyze the aromatic ring cleavage of PHEN, using the intermediates as substrates, transforming them into less harmful and more biodegradable compounds. This could help reduce environmental pollution and mitigate health risks associated with PAH exposure. The potential of these enzymes for biotechnological applications is also highlighted, emphasizing their critical role in understanding PAH degradation by white-rot fungi.