scholarly journals Impact of pollutant as selection pressure on conjugative transfer of dioxin-catabolic plasmids harbored by Rhodococcus sp. strain p52

2021 ◽  
Author(s):  
Gang Zhao ◽  
Yanan Wu ◽  
Xu Wang ◽  
Meng Chen ◽  
Li Li
Keyword(s):  
Activated Sludge ◽  
Selection Pressure ◽  
Environmental Pollutants ◽  
Plasmid Transfer ◽  
Catabolic Plasmid ◽  
The Difference ◽  
Genetic Bioaugmentation ◽  
Catabolic Plasmids ◽  
Activated Sludge Bacteria

Abstract Plasmid-mediated bioaugmentation has potential application in the cleanup of recalcitrant environmental pollutants. In this study, we examined the influence of various contaminants (in different categories or different amounts) as a selection pressure on the transfer of catabolic plasmids within an activated sludge bacteria community bioaugmented with Rhodococcus sp. strain p52 harboring pDF01 and pDF02. The distinguishable genera of transconjugants were isolated under the stresses of phenanthrene, dibenzothiophene, and dibenzo-p-dioxin. The difference in genomic G + C content (5.0 ~ 27.5%) between transconjugants and strain p52 indicated the transfer of the catabolic plasmids crossing phylogenetic boundaries. The specific removal rates in activated sludge reactors for phenanthrene, dibenzothiophene, and dibenzo-p-dioxin were elevated in turn. The three contaminants exerted different degrees of influence on the activated sludge bacteria bearing the catabolic plasmids. The highest proportion of transconjugants was detected in the reactor fed with dibenzo-p-dioxin. Additionally, as dibenzo-p-dioxin from 10 to 80 mg/L was fed into the reactors, the proportion of transconjugants increased. Film mating tests demonstrated that the plasmid transfer frequency varied among recipients under the contaminant stresses of phenanthrene, dibenzothiophene, and dibenzo-p-dioxin. Our study provides a characterization of the recalcitrant contaminants as a selection pressure that can modulate catabolic plasmid transfer during genetic bioaugmentation for the removal of contaminants.

Characterization of the loosely attached fraction of activated sludge bacteria

2008 ◽  
Vol 42 (4-5) ◽  
pp. 843-854 ◽  
Author(s):  
Fernando Morgan-Sagastume ◽  
Poul Larsen ◽  
Jeppe Lund Nielsen ◽  
Per Halkjær Nielsen
Keyword(s):  
Activated Sludge ◽  
Activated Sludge Bacteria

Genetic Bioaugmentation of Activated Sludge with Dioxin-Catabolic Plasmids Harbored byRhodococcussp. Strain p52

2018 ◽  
Vol 52 (9) ◽  
pp. 5339-5348 ◽  
Author(s):  
Chongyang Ren ◽  
Yiying Wang ◽  
Lili Tian ◽  
Meng Chen ◽  
Jiao Sun ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Genetic Bioaugmentation ◽  
Catabolic Plasmids

Potential of predominant activated sludge bacteria as recipients in conjugative plasmid transfer

2005 ◽  
Vol 100 (6) ◽  
pp. 600-605 ◽  
Author(s):  
Daisuke Inoue ◽  
Kazunari Sei ◽  
Satoshi Soda ◽  
Michihiko Ike ◽  
Masanori Fujita
Keyword(s):  
Activated Sludge ◽  
Plasmid Transfer ◽  
Conjugative Plasmid ◽  
Conjugative Plasmid Transfer ◽  
Activated Sludge Bacteria

scholarly journals Host Range of the Conjugative Transfer System of IncP-9 Naphthalene-Catabolic Plasmid NAH7 and Characterization of Its oriT Region and Relaxase

2016 ◽  
Vol 83 (1) ◽  
Author(s):  
Kouhei Kishida ◽  
Kei Inoue ◽  
Yoshiyuki Ohtsubo ◽  
Yuji Nagata ◽  
Masataka Tsuda
Keyword(s):  
Host Range ◽  
Broad Host Range ◽  
Conjugative Transfer ◽  
Bacterial Strains ◽  
Conjugation System ◽  
Independent Manner ◽  
Content Type ◽  
Catabolic Plasmid ◽  
Catabolic Plasmids

ABSTRACT NAH7 and pWW0 from gammaproteobacterial Pseudomonas putida strains are IncP-9 conjugative plasmids that carry the genes for degradation of naphthalene and toluene, respectively. Although such genes on these plasmids are well-characterized, experimental investigation of their conjugation systems remains at a primitive level. To clarify these conjugation systems, in this study, we investigated the NAH7-encoded conjugation system by (i) analyzing the origin of its conjugative transfer (oriT)-containing region and its relaxase, which specifically nicks within the oriT region for initiation of transfer, and (ii) comparing the conjugation systems between NAH7 and pWW0. The NAH7 oriT (oriT N) region was located within a 430-bp fragment, and the strand-specific nicking (nic) site and its upstream sequences that were important for efficient conjugation in the oriT N region were identified. Unlike many other relaxases, the NAH7 relaxase exhibited unique features in its ability to catalyze, in a conjugation-independent manner, the site-specific intramolecular recombination between two copies of the oriT N region, between two copies of the pWW0 oriT (oriT W) region (which is clearly different from the oriT N region), and between the oriT N and oriT W regions. The pWW0 relaxase, which is also clearly different from the NAH7 relaxase, was strongly suggested to have the ability to conjugatively and efficiently mobilize the oriT N-containing plasmid. Such a plasmid was, in the presence of the NAH7Δnic derivative, conjugatively transferable to alphaproteobacterial and betaproteobacterial strains in which the NAH7 replication machinery is nonfunctional, indicating that the NAH7 conjugation system has a broader host range than its replication system. IMPORTANCE Various studies have strongly suggested an important contribution of conjugative transfer of catabolic plasmids to the rapid and wide dissemination of the plasmid-loaded degradation genes to microbial populations. Degradation genes on such plasmids are often loaded on transposons, which can be inserted into the genomes of the recipient bacterial strains where the transferred plasmids cannot replicate. The aim was to advance detailed molecular knowledge of the determinants of host range for plasmids. This aim is expected to be easily and comprehensively achieved using an experimental strategy in which the oriT region is connected with a plasmid that has a broad host range of replication. Using such a strategy in this study, we showed that (i) the NAH7 oriT-relaxase system has unique properties that are significantly different from other well-studied systems and (ii) the host range of the NAH7 conjugation system is broader than previously thought.

Analisis Karakterisasi Teknologi Direct Sequence Spread Spectrum Dan Frequency Hopping Spread Spectrum

2019 ◽  
Vol 2 (2) ◽  
pp. 129-138
Author(s):  
Fawzan Galib Abdul Karim Bawahab ◽  
Elvan Yuniarti ◽  
Edi Kurniawan
Keyword(s):  
Spread Spectrum ◽  
Communication Systems ◽  
Multiple Access ◽  
Frequency Hopping ◽  
Direct Sequence Spread Spectrum ◽  
Direct Sequence ◽  
Frequency Hopping Spread Spectrum ◽  
Two Systems ◽  
The Difference

Abstrak. Pada penelitian ini, telah dilakukan analisa karakterisasi pada teknologi Direct Sequence Spread Spectrum dan Frequency Hopping Spread Spectrum, sebagai salah satu teknik multiple-access pada sistem komunikasi. Karakterisasi dilakukan untuk mencari bagaimana cara meningkatkan keoptimalan kedua sistem tersebut, dalam mengatasi masalah interferensi dengan sistem dan channel yang sama. Dan juga untuk menentukan veriabel apa yang mempengaruhi keoptimalan kedua sistem tersebut. Karakterisasi dilakukan dengan menentukan variabel-variabel yang mempengaruhi keoptimalan keduanya. Hasil dari karakterisasi, diketahui variabel-variabel yang mempengaruhi kemampuan sistem DSSS yaitu nilai frekuensi spreading (). Sedangkan untuk sistem FHSS yaitu nilai frekuensi spreading ( dan ) dan selisih antara frekuensi hopping data dengan frekuensi hopping interferensi . Kata Kunci: BER, DSSS, FHSS, Interference, Spread spectrum. Abstract. In this study, characterization of Direct Sequence Spread Spectrum and Frequency Hopping Spread Spectrum technologies have been done, as one of the multiple-access techniques in communication systems. Characterization is done to find out how to improve the ability of the two systems, in solving interference problems with the same system and channel. And also to determine what veriabel affects the ability of the two systems. Characterization is done by determining the variables that affect the ability of both. The results of the characterization, known variables that affect the ability of the DSSS system are the spreading frequency value (). As for the FHSS system, the spreading frequency value ( and ) and the difference between frequency hopping data with frequency hopping interference .

Enrichment and characterization of an anaerobic methyl ethyl ketoxime degrading culture from an anoxic/anaerobic/aerobic activated sludge sequencing batch reactor

1998 ◽  
Vol 37 (4-5) ◽  
pp. 95-98 ◽  
Author(s):  
Nancy G. Love ◽  
Mary E. Rust ◽  
Kathy C. Terlesky
Keyword(s):  
Energy Source ◽  
Activated Sludge ◽  
Electron Acceptor ◽  
Sequencing Batch Reactor ◽  
Enrichment Culture ◽  
Batch Reactor ◽  
Nitrification Inhibitor ◽  
Time Frame ◽  
Methyl Ethyl

An anaerobic enrichment culture was developed from an anoxic/anaerobic/aerobic activated sludge sequencing batch reactor using methyl ethyl ketoxime (MEKO), a potent nitrification inhibitor, as the sole carbon and energy source in the absence of molecular oxygen and nitrate. The enrichment culture was gradually fed decreasing amounts of biogenic organic compounds and increasing concentrations of MEKO over 23 days until the cultures metabolized the oxime as the sole carbon source; the cultures were maintained for an additional 41 days on MEKO alone. Turbidity stabilized at approximately 100 mg/l total suspended solids. Growth on selective media plates confirmed that the microorganisms were utilizing the MEKO as the sole carbon and energy source. The time frame required for growth indicated that the kinetics for MEKO degradation are slow. A batch test indicated that dissolved organic carbon decreased at a rate comparable to MEKO consumption, while sulfate was not consumed. The nature of the electron acceptor in anaerobic MEKO metabolism is unclear, but it is hypothesized that the MEKO is hydrolyzed intracellularly to form methyl ethyl ketone and hydroxylamine which serve as electron donor and electron acceptor, respectively.

Characterization of the surface of hydrodesulphurization catalysts by adsorption of hydrocarbons

1984 ◽  
Vol 49 (2) ◽  
pp. 410-420
Author(s):  
Eva Hillerová ◽  
Miroslav Zdražil
Keyword(s):  
Hydrogen Sulphide ◽  
Chromatographic Method ◽  
Supported Catalysts ◽  
Alumina Surface ◽  
Reversible Adsorption ◽  
The Difference

Reversible adsorption of heptane and benzene on model and industrial hydrodesulphurization molybdena catalysts has been studied by elution chromatographic method at 150 °C. An increase in the adsorption of heptane on sulphidation of adsorbents was small for Al2O3 and great for MoO3. Supported catalysts behaved as mixture of Al2O3 and MoO3.The portion of surface which can be transformed by sulphidation into MoS2 ranged from 0 to 65% for individual commercial catalysts, as determined from the change in heptane adsorption after sulphidation of a given sample. The polarity of catalysts, including their acidity, was estimated from the difference between adsorption of benzene and heptane. The polarity of model and industrial catalysts in oxidic form was similar to that of alumina in most cases. The decrease in the polarity after sulphidation of the adsorbents was small for Al2O3 and great for MoO3. The decrease in polarity resulting from sulphidation of supported catalysts was relatively small, since the reaction of MoO3 monolayer with hydrogen sulphide leads to partial reformation of the alumina surface. The acidity of supported sulphided hydrodesulphurization catalysts has been shown by this method to be comparable with the acidity of the support itself.

Synthesis and characterization of a series of 1-methyl-4-[2-aryl-1-diazenyl]piperazines and a series of ethyl 4-[2-aryl-1-diazenyl]-1-piperazinecarboxylates

2004 ◽  
Vol 82 (8) ◽  
pp. 1294-1303 ◽  
Author(s):  
Vanessa Renée Little ◽  
Keith Vaughan
Keyword(s):  
Free Energy ◽  
Chemical Shifts ◽  
Linear Free Energy Relationship ◽  
Piperazine Ring ◽  
Linear Free Energy ◽  
In Series ◽  
Methylene Groups ◽  
Diazonium Coupling ◽  
The Difference

1-Methylpiperazine was coupled with a series of diazonium salts to afford the 1-methyl-4-[2-aryl-1-diazenyl]piperazines (2), a new series of triazenes, which have been characterized by 1H and 13C NMR spectroscopy, IR spectroscopy, and elemental analysis. Assignment of the chemical shifts to specific protons and carbons in the piperazine ring was facilitated by comparison with the chemical shifts in the model compounds piperazine and 1-methylpiperazine and by a HETCOR experiment with the p-tolyl derivative (2i). A DEPT experiment with 1-methylpiperazine (6) was necessary to distinguish the methyl and methylene groups in 6, and a HETCOR spectrum of 6 enabled the correlation of proton and carbon chemical shifts. Line broadening of the signals from the ring methylene protons is attributed to restricted rotation around the N2-N3 bond of the triazene moiety in 2. The second series of triazenes, the ethyl 4-[2-phenyl-1-diazenyl]-1-piperazinecarboxylates (3), have been prepared by similar diazonium coupling to ethyl 1-piperazinecarboxylate and were similarly characterized. The chemical shifts of the piperazine ring protons are much closer together in series 3 than in series 2, resulting in distortion of the multiplets for these methylenes. It was noticed that the difference between these chemical shifts in 3 exhibited a linear free energy relationship with the Hammett substituent constants for the substituents in the aryl ring. Key words: triazene, piperazine, diazonium coupling, NMR, HETCOR, linear free energy relationship.

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