Naphthalene Degradation Research Articles

Zinc sulfide quantum dots as powerful and efficient nanophotocatalysts for the removal of industrial pollutant

In this work, a simple, efficient and powerful photocatalytic methodology based on application of pure zinc sulfide (ZnS) quantum dots (QDs) is presented for the removal of naphthalene, as a model molecule of industrial pollutants. A facile room-temperature precipitation method was applied for the synthesis of ZnS QDs, in the presence of 2-mercaptoethanol as capping agents. The characterization of the prepared QDs was carried out by X-ray diffraction (XRD), transmission electron microscopy, high-resolution scanning electron microscopy, scanning tunneling microscopy, fluorescence, and UV–Vis absorption spectroscopies. The XRD investigations indicated that the prepared ZnS QDs are crystalline, with cubic zinc blend structure, with the average particle diameters of 1.2 nm. The fluorescence and UV–Vis absorption investigations showed a narrow and sharp emission band at 424 nm with a broad adsorption band around 235 nm. In addition, the prepared ZnS QDs were used as nanophotocatalysts, for the removal of naphthalene, as a model molecule. The influence of the experimental parameters on the removal efficiency of the ZnS QDs was studied. According to the results, the highest photocatalytic degradation of naphthalene in the presence of ZnS QDs (>95 %) was obtained at alkaline pH, in the presence of 10 mg of QDs, after a reasonable reaction time.

Complete Genome Sequence of Pseudomonas balearica DSM 6083T.

The whole-genome sequence of Pseudomonas balearica SP1402 (DSM 6083T) has been completed and annotated. It was isolated as a naphthalene degrader from water of a lagooning wastewater treatment plant. P. balearica strains tolerate up to 8.5% NaCl and are considered true marine denitrifiers.

Enrichment and identification of naphthalene-degrading bacteria from the Persian Gulf

Naphthalene is a ubiquitous pollutant of the marine environment, and naphthalene biodegradation has been receiving constant scientific consideration. For cleanup of aromatic contaminated sites, bioremediation methods are considered as economical and safe approaches for the marine environment. The aims of this research are isolation and characterization of naphthalene-degrading bacteria from some marine samples of the Persian Gulf. Fifty four naphthalene-degrading bacteria were isolated from marine samples (sediment and seawater) that are enriched in ONR7a medium with naphthalene as the only carbon source. Some screening tests such as growth at high concentration of naphthalene, bioemulsifier production and surface hydrophobicity were done to select the best and prevalent strains for naphthalene degradation. Determination of the nucleotide sequence of the gene encoding for 16S rRNA shows that these isolated strains belong to these genera: Shewanella, Salegentibacter, Halomonas, Marinobacter, Oceanicola, Idiomarina and Thalassospira. These strains can degrade half of the percentage of naphthalene in 10days of incubation. This research is the first report on isolation of these genera from the Persian Gulf as naphthalene-degrader.

Draft Genome Sequence of Pseudomonas stutzeri ODKF13, Isolated from Farmland Soil in Alvin, Texas.

Pseudomonas stutzeri ODKF13 is a bacterial microorganism isolated from farmland soil in Alvin, Texas. This strain is notable for its naphthalene degradation and nitrogen fixation pathways and for its characterization as an organophosphate degrader of phosphotriester and phosphorothioate insecticides.

Synthesis of N and La co-doped TiO2/AC photocatalyst by microwave irradiation for the photocatalytic degradation of naphthalene

La and N co-doped TiO2 nanoparticles supported on activated carbon (TiO2/AC) were synthesized through a microwave-assisted sol–gel method for the synergistic removal of naphthalene solution by photocatalytic degradation. Results showed that the La and N ions were incorporated into the TiO2 framework in both the anatase and rutile phases of TiO2 for single doped and co-doped samples, which narrowed the band gap of TiO2 from 2.82 to 2.20 eV. The PL spectra of the samples showed a decrease in the recombination centers when N and La were introduced in TiO2/AC. The 0.001La-N-TiO2/AC photocatalyst exhibited the highest degradation efficiency of 93.5% for naphthalene under visible light within 120 min. This result was attributed to a synergistic effect involving the efficient inhibition of the recombination of photogenerated electrons and holes, the increase in surface hydroxyl, surface area, volume pores, and the increase of uptake in the visible light region. In addition, the high apparent rate constant indicated that La and N co-doping result in the increase of photoactivity. This study demonstrated the co-doped TiO2/AC is a highly efficient photocatalyst for the removal of naphthalene. The results provided valuable information on the mechanism of naphthalene decomposition.

Gamma radiolytic degradation of naphthalene in aqueous solution

Abstract The decomposition of naphthalene in aqueous solution was studied using gamma irradiation combined with both H2O2 and TiO2 nanoparticles. Gamma irradiation led to a complete degradation of naphthalene and a partial mineralization. With initial concentration of 5–32 mg/L, more than 98% of naphthalene was removed and TOC reduction reached 28–31% at an absorbed dose of 3.0 kGy. The degradation of naphthalene was faster at neutral pH and the initial degradation rate increased with increasing the initial concentration of naphthalene. Addition of H2O2 and TiO2 nanoparticles all enhanced the degradation and mineralization of naphthalene. TOC removal efficiency increased from 28% (irradiation alone) to 35% with addition of H2O2 (40 mg/L), and to 48% with addition of TiO2 (0.8 g/L). The degradation of naphthalene in aqueous solution by gamma irradiation was mainly through the oxidation by ·OH radicals. The intermediate naphthol and carboxylic acids such as formic acid and oxalic acid were identified by LC–MS and IC.

A novel Pseudomonas gessardii strain LZ-E simultaneously degrades naphthalene and reduces hexavalent chromium

Combined pollutants with polycyclic aromatic hydrocarbons (PAHs) and heavy metals have been identified as toxic and unmanageable contaminates. In this work, Pseudomonas gessardii strain LZ-E isolated from wastewater discharge site of a petrochemical company degrades naphthalene and reduces Cr(VI) simultaneously. 95% of 10mgL−1 Cr(VI) was reduced to Cr(III) while 77% of 800mgL−1 naphthalene was degraded when strain LZ-E was incubated in BH medium for 48h. Furthermore, naphthalene promotes Cr(VI) reduction in strain LZ-E as catechol and phthalic acid produced in naphthalene degradation are able to reduce Cr(VI) abiotically. An aerated bioreactor system was setup to test strain LZ-E’s remediation ability. Strain LZ-E continuously remediated naphthalene and Cr(VI) at rates of 15mgL−1h−1 and 0.20mgL−1h−1 of 800mgL−1 naphthalene and 10mgL−1 Cr(VI) addition with eight batches in 16days. In summary, strain LZ-E is a potential applicant for combined pollution remediation.

Naphthalene degradation by catalytic ozonation based on nickel oxide: study of the ethanol as cosolvent.

Naphthalene (NA) is a polycyclic aromatic hydrocarbon with toxic properties in aquatic systems. Ozonation (O3) and catalytic ozonation (O3-cat) processes are attractive alternatives of degradation for this kind of compound. NA (20mgL-1) degradation by conventional and catalytic ozonation in the presence of a cosolvent (ethanol) was the aim of this study. This solution was proposed to simulate some aspects of real wastewaters where not only water acts as solvent. Two proportions of the mixture ethanol/water were selected (30:70 and 50:50) with the purpose of studying the cosolvent effect on NA degradation system by ozonation. O3-cat process used nickel oxide as catalyst (0.1gL-1). The degradation analysis of NA by O3-cat in two different proportions of cosolvent showed that in the case of 30:70 (ethanol/water), a 95% of NA elimination in 60min was obtained, while in the case 50:50 (ethanol/water), only 55% was achieved. The O3 process showed similar results of degradation to the initial compound in comparison with catalytic system. According to these results, there is an inhibition effect in pollutant removal by ethanol due to the higher ethanol concentration; the lower elimination rate of NA was obtained (by 40% during the 60min). The by-products analysis of ozonation process detected oxalic and formic acids. Treatments with NiO presented less production of organic acids in comparison with conventional ozonation process. The high concentration of ethanol has a relevant factor in the elimination of NA and formation of organic acids; samples with 50% of cosolvent have showed a higher concentration of organic acids. X-ray photoelectron spectroscopy (XPS) study of O3-cat of diluent (O3-NiO control) and O3-NA-NiO showed the presence of -CO3 absorbed on catalyst due to ethanol decomposition.

Depolymerizing Activities of Aromatic Hydrocarbon Degrading Phyllosphere Fungi in Sri Lanka

Application of aromatic hydrocarbon degrading fungi to bioremediate aromatic hydrocarbonic (AH) pollutants is a current trend and many research on the use of such fungi to remediate aromatic hydrocarbonic pollutants in temperate situations have been reported. Bioremediation of these hydrocarbons is through an array of lignolitic and non lignolitic extra cellular enzymes. Therefore, the present investigation attempts to assess lignolytic and non lignolytic enzyme activities of selected phyllosphere aromatic hydrocarbon degrading fungi during the aromatic hydrocarbon degradation. In a previous research aromatic hydrocarbon degrading fungi were isolated from ornamental leaf samples collected from highly urbanized and industrialized areas of Sri Lanka. These fungal species were then selected to evaluate their enzyme activities when degrading aromatic hydrocarbons. They were screened for their manganese dependent peroxidases (Mnp), Lignin peroxidases (Lip) and laccases enzyme activities. Most efficient naphthalene degrading fungi showed Mnp and Lip enzyme activities. The best naphthalene degrader, Penicillium oxalicum showed significantly higher Mnp (26 Uml-1 min-1) activity during naphthalene degradation process. However, phenanthrene degrading phyllosphere fungal strains showed higher laccase activities. Penicillium oxalicum showed significantly higher laccase activity during the phenanthrene degradation showing the same fungal species had different enzyme predominant pathways for different xenobiotics. Same fungal species performed differently for different AH substrates. Mnp was the predominantly used enzyme in the most efficient naphthalene degrading fungal species and phenanthrene degradation of them was manipulated by laccases. The promising results of the present investigation will broaden the perspective of ecofriendly practical application of the above fungal strains at environmental sites where contamination is caused by AHs especially, phenanthrene, naphthalene, toluene and xylene. Also this opens many avenues for conducting future research in the field of bioremediation and biodegradation.

Genetic Basis of Naphthalene and Phenanthrene Degradation by Phyllosphere Bacterial Strains Alcaligenes faecalis and Alcaligenes sp. 11SO

Two bacterial strains, Alcaligenes feacalis and Alcaligenes sp. 11SO isolated from the phyllosphere of four ornamental plant species, Ixora chinensis, Ervatamia divaricata, Hibiscus rosa-sinensis and Amaranthus cruentus found in five highly polluted sites in Sri Lanka, showed a higher level of phenanthrene and naphthalene degradation ability. Both these strains harbor plasmids conferring them resistance to ampicillin. Curing of these strains of their plasmid drastically reduced the ability to degrade the hydrocarbons. Upon transformation of these plasmids into E.coli JM109 enable it to degrade the two hydrocarbons efficiently. Plasmid encoded phenanthrene and naphthalene degradation suggested the presence of required catabolic genes in these plasmids. PCR amplification with degenerate primers and comparison of their nucleotide sequences with Genbank sequences indicated that plasmids of those bacterial strains harbor the genes nahR, nahU involved in naphthalene degradation and phnG for phenanthrene degradation. RFLP and nucleotide sequence comparison of nahU and nahR amplicons revealed that both of these genes in two bacterial strains are homologous. But, phnG gene copies of two bacterial strains exist as two distinct alleles.

Preparation and photocatalytic activity of WO3–MWCNT nanocomposite for degradation of naphthalene under visible light irradiation

Preparation and application of the novel and high performance WO3–MWCNT photocatalyst for photodegradation of naphthalene under visible light irradiation.

Use of mass spectrometry for characterizing the growth of Pseudomonas bacteria bearing naphthalene degradation plasmids

Major metabolites formed by Pseudomonas bacteria bearing various naphthalene degradation plasmids were identified using high performance liquid chromatography and mass spectrometry in combination with electrospray ionization. During the growth of P. aureofaciens BS1393(NPL-41) bacteria bearing the plasmid NPL-41, partial oxidation of naphthalene was shown to occur to form the major exometabolite (salicylate) and minor exometabolite (phenol). The growth of P. aureofaciens BS1393(pOV17) bacteria bearing the plasmid pOV17 was accompanied by complete oxidation of naphthalene and formation of trace amounts of salicylate and epoxybenzene. Based on the data of molecular mass spectrometry, we determined the dynamics of CO2 production and oxygen uptake in the process of bacterial growth. The specific quantity of CO2 per unit of cell amount for P. aureofaciens BS1393(NPL-41) bacteria was shown to exceed fivefold that for P. aureofaciens BS1393(pOV17). The respiratory quotient (RQ) representing the ratio of the molar concentrations of metabolic CO2 to consumed oxygen depends on the type of plasmids that determine naphthalene degradation. The value of RQ during the growth of P. aureofaciens BS1393(pOV17) bacteria was almost 1.5 times greater than in the case of P. aureofaciens BS1393(NPL-41). The ratio of O2 uptake to CO2 formed by the first culture was 4.5 mol O2/mol CO2; by the second culture, 6.5 mol O2/mol CO2.

Genome sequencing reveals mechanisms for heavy metal resistance and polycyclic aromatic hydrocarbon degradation in Delftia lacustris strain LZ-C

Strain LZ-C, isolated from a petrochemical wastewater discharge site, was found to be resistant to heavy metals and to degrade various aromatic compounds, including naphenol, naphthalene, 2-methylnaphthalene and toluene. Data obtained from 16S rRNA gene sequencing showed that this strain was closely related to Delftia lacustris. The 5,889,360bp genome of strain LZ-C was assembled into 239 contigs and 197 scaffolds containing 5855 predicted open reading frames (ORFs). Among these predicted ORFs, 464 were different from the type strain of Delftia. The minimal inhibitory concentrations were 4mM, 30µM, 2mM and 1mM for Cr(VI), Hg(II), Cd(II) and Pb(II), respectively. Both genome sequencing and quantitative real-time PCR data revealed that genes related to Chr, Czc and Mer family genes play important roles in heavy metal resistance in strain LZ-C. In addition, the Na(+)/H(+) antiporter NhaA is important for adaptation to high salinity resistance (2.5M NaCl). The complete pathways of benzene and benzoate degradation were identified through KEGG analysis. Interestingly, strain LZ-C also degrades naphthalene but lacks the key naphthalene degradation gene NahA. Thus, we propose that strain LZ-C exhibits a novel protein with a function similar to NahA. This study is the first to reveal the mechanisms of heavy metal resistance and salinity tolerance in D. lacustris and to identify a potential 2-methylnaphthalene degradation protein in this strain. Through whole-genome sequencing analysis, strain LZ-C might be a good candidate for the bioremediation of heavy metals and polycyclic aromatic hydrocarbons.

Enhancement of naphthalene tolerance in transgenic Arabidopsis plants overexpressing the ferredoxin-like protein (ADI1) from rice

The ADI1 Arabidopsis plants enhanced tolerance and degradation efficiency to naphthalene and had great potential for phytoremediation of naphthalene in the plant material before composting or harvesting and removal. Naphthalene is a global environmental concern, because this substance is assumed to contribute considerably to human cancer risk. Cleaning up naphthalene contamination in the environment is crucial. Phytoremediation is an efficient technology to clean up contaminants. However, no gene that can efficiently degrade exogenous recalcitrant naphthalene in plants has yet been discovered. Ferredoxin (Fd) is a key player of biological electron transfer reaction in the PAH degradation process. The biochemical pathway for bacterial degradation of naphthalene has been well investigated. In this study, a rice gene, ADI1, which codes for a putative photosynthetic-type Fd, has been transformed into Arabidopsis thaliana. The transgenic Arabidopsis plants enhanced tolerance and degradation efficiency of naphthalene. Compared with wild-type plants, transgenic plants assimilated naphthalene from the culture media faster and removed more of this substance. When taken together, our findings suggest that breeding plants with overexpressed ADI1 gene is an effective strategy to degrade naphthalene in the environment.

Bioaugmentation with isolated strains for the removal of toxic and refractory organics from coking wastewater in a membrane bioreactor.

The bioaugmentation strains for phenol, pyridine, quinoline, carbazole, and naphthalene degradation were employed to treat coking wastewater in a membrane bioreactor (MBR). The results showed that the bioaugmented MBR was much better in pollutant removal than that of the control MBR with conventional activated sludge. Compared to the control MBR, the bioaugmented MBR displayed an additional 3.2 mg/L of phenol, pyridine, quinoline, naphthalene and carbazole in total by the addition of the degrading strains. Also, about 10 % of the chemical oxygen demand in the effluent was further removed by the bioaugmentation. The pyrosequencing analysis of the sludge in the MBRs revealed that the microbial community shifted in response to the addition of the degrading strains. The diversity of the microbial community increased during the bioaugmentation, and some bacterial taxa favorable to the removal of toxic and refractory pollutants appeared in the bioaugmented MBR. The results indicated that the use of high-efficiency bacteria was a feasible method for industrial coking wastewater treatment.

A fusant of Amycolatopsis sp. M3-1 and Pseudomonas sp. Nai8 with high capacity of degrading novel pyrimidynyloxybenzoic herbicide ZJ0273 and naphthalene.

ZJ0273 (propyl 4-(2-(4, 6-demethoxy pyrimidin-2-yloxy) benzylamino) benzoate) is a novel pyrimidynyloxybenzoic-based herbicide developed in China for oilseed crop. This study was aimed to construct new strains capable of degrading naphthalene and ZJ0273 by protoplast fusion between Amycolatopsis sp. M3-1 and Pseudomonas sp. Nai8. Eight recombinant strains were successfully produced, and the strains could simultaneously utilize ZJ0273 and naphthalene as the sole carbon and energy source, respectively. One of recombinant strains, MN6 with higher degrading efficiency, was chosen for further study. Under the condition of pH 7.0, 30 °C, ZJ0273 and naphthalene degradation percent by the recombinant strain MN6 could reach 65.10% (20 days) and 88.46% (48 h), respectively. According to the identified six metabolites (M1-M6) by LC-MS/MS, biodegradation pathway of ZJ0273 was proposed. ZJ0273 biodegradation catalyzed by the recombinant strain MN6 involved continuous biocatalytic reactions such as de-estering, hydrolysis, acylation, C-N cleavage, de-methyl, and ether cleavage reactions.

THE POTENCY OF LOCAL ISOLATES FROM NORTH SUMATERA IN THE DEGRADATION OF NAPHTALENE

<p>The potency of biosurfactant–producing bacteria isolated from oil-contaminated coast, Belawan North Sumatera, in the degradation of hydrocarbon compound such as naphthalene has been studied. Thirteen isolates has been obtained using Bushnell Haas Agar containing 2% naphthalene as the sole carbon source. The bacterial growth was observed using Standard Plate Count method. The ability of each isolates to produce bioactive-surface compound was determined. A drop-collapsing test was performed to examine the activity of each biosurfactant. All isolates tested grew well in Bushnell Haas Broth medium. Among those, two isolates were able to remove almost all (99%) naphthalene from the medium during 15 days. Those two isolates have also shown highest concentration of biosurfactant production which is 75.180 ppm.</p><p><br /><strong>Keywords</strong>: local isolates, biosurfactant, naphthalene degradation.</p>

Characterization of a protocatechuate catabolic gene cluster in Rhodococcus ruber OA1 involved in naphthalene degradation

In this study, we investigated a protocatechuate catabolic gene cluster involved in naphthalene degradation in Rhodococcus ruber OA1. Rhodococcus ruber OA1 was isolated from the pharmaceutical wastewater treatment plant of Xinhua Pharmaceutical Co., Ltd. (Zibo, China). Substrate utilization tests showed that OA1 utilizes naphthalene, phenol, benzoate, salicylate, and protocatechuate as the sole carbon and energy sources for growth. A degradation assay revealed that phthalate is an intermediate in naphthalene degradation and that the protocatechuate pathway plays an important role in naphthalene degradation. To determine the genetic basis and regulation of protocatechuate catabolism in OA1, a fosmid genomic library was constructed and a positive clone carrying the protocatechuate degradation gene cluster was isolated. Sequencing and a bioinformatics analysis identified the complete gene cluster, pcaJIGHBARC, responsible for protocatechuate degradation. Based on this gene cluster, the genes pcaGH (encoding the α and β subunits of protocatechuate 3,4-dioxygenase, 3,4-PCD) were coexpressed and the expressed products showed 3,4-PCD activity. This study illustrates a potential pathway of naphthalene degradation and identifies a protocatechuate pathway in Rhodococcus ruber OA1 for the first time, thus extending our understanding of polycyclic aromatic hydrocarbon degradation and the related aromatic compounds degraded in the process.

Biodegradation of Various Aromatic Compounds by Enriched Bacterial Cultures: Part A–Monocyclic and Polycyclic Aromatic Hydrocarbons

Present study focused on the screening of bacterial consortium for biodegradation of monocyclic aromatic hydrocarbon (MAH) and polycyclic aromatic hydrocarbons (PAHs). Target compounds in the present study were naphthalene, acenaphthene, phenanthrene (PAHs), and benzene (MAH). Microbial consortia enriched with the above target compounds were used in screening experiments. Naphthalene-enriched consortium was found to be the most efficient consortium, based on its substrate degradation rate and its ability to degrade other aromatic pollutants with significantly high efficiency. Substrate degradation rate with naphthalene-enriched culture followed the order benzene > naphthalene > acenaphthene > phenanthrene. Chryseobacterium and Rhodobacter were discerned as the predominant species in naphthalene-enriched culture. They are closely associated to the type strain Chryseobacterium arthrosphaerae and Rhodobacter maris, respectively. Single substrate biodegradation studies with naphthalene (PAH) and benzene (MAH) were carried out using naphthalene-enriched microbial consortium (NAPH). Phenol and 2-hydroxybenzaldehyde were identified as the predominant intermediates during benzene and naphthalene degradation, respectively. Biodegradation of toluene, ethyl benzene, xylene, phenol, and indole by NAPH was also investigated. Monod inhibition model was able to simulate biodegradation kinetics for benzene, whereas multiple substrate biodegradation model was able to simulate biodegradation kinetics for naphthalene.

Quantitative analysis of cellular proteome alterations of Pseudomonas putida to naphthalene-induced stress.

To investigate whether genes other than the operons nahAaAbAcAdBFCED and nahGTHINLOMKJ of Pseudomonas putida are involved in the tolerance of the bacterium to naphthalene. Cellular responses of P. putida ND6 grown with 2 and 4 g naphthalene/l were investigated using a quantitative proteomic-based approach. Comparative analysis of the proteome data identified that the expression levels of 22 proteins involved in heat shock and universal stress response, naphthalene degradation, cell envelope synthesis, and motility were up-regulated; while the expression levels of 26 proteins involved in protein and fatty acid synthesis, carbon compound, nucleotide, and amino acid metabolism, and small molecule transport were down-regulated. Our findings offer insights into the cellular response of P. putida to high naphthalene concentrations at the protein level.