Presence Of Various Metal Ions Research Articles

Horizontal Transfer of a Novel Soil Agarase Gene from Marine Bacteria to Soil Bacteria via Human Microbiota.

Seaweed is receiving an increasing amount of attention as a “sea vegetable”. The microbiota of coastal populations may acquire seaweed associated enzymes through marine food. Several agarases have been found in non-marine environments; however, their origin is unknown. In this study, a hypothetical protein, Aga1, was identified as an agarase from an inland soil agar-degrading bacterium, Paenibacillus sp. SSG-1.Having low similarity to known glycoside hydrolases, Aga1 may be a distant member of the glycoside hydrolase family 86. Aga1 has good pH stability (pH 3–11) and is stable in the presence of various metal ions. Aga1 is an exo-type β-agarase that produces NA 4 (neoagarotetraose) and NA 6 (neoagarohexaose) as its main products. In addition, Aga1 may be a cell-surface-binding protein. The bioinformatic analysis showed aga1 may have been transfered together with its surrounding genes, from marine bacteria to soil bacteria via human microbiota. The use of seaweed as food and the disposal of human faeces or saliva were the most likely reasons for this gene transfer pathway. Notably, the results also indicated that microbes from inland humans may degrade agar and that these microbes may have acquired seaweed associated genes because of increased seaweed in diets.

Clonación, expresión y caracterización de una nueva esterasa derivada de metagenomas de suelos agrícolas colombianos

El presente trabajo tuvo como objetivo la bioprospección de ADN metagenómico derivado de comunidades microbianas asociadas a un agroecosistema de importancia nacional. Este análisis permitió realizar la producción, expresión, purificación y caracterización de una enzima novedosa con actividad esterasa. Esta enzima, denominada LipM, había sido previamente identificada en clones metagenómicos derivados de suelos dedicados al cultivo de papa criolla (Solanum pureja), mediante secuencia de nueva generación y análisis bioinformáticos. La secuencia codificante de la enzima fue clonada en el vector pBADgiii y expresada en E. coli como sistema de expresión, lo que permitió optimizar el proceso de producción recombinante y su posterior purificación.Funcionalmente la enzima presentó una mayor afinidad por sustratos de p-nitrofenil con ácidos grasos de cadena corta (<C8). LipM mostró completa funcionalidad a temperaturas entre 30 – 37 ºC y en valores de pH cercanos al fisiológico (entre 7.0 y 8.0). Igualmente, esta enzima exhibió buena estabilidad en presencia de varios iones metálicos, inhibidores y 0.1% (p/v) de SDS. Su alto nivel de estabilidad en presencia de iones metálicos e inhibidores, así como su particular especificidad en cuanto a sustratos, la hacen una enzima óptima para utilización en diferentes aplicaciones biotecnológicas.Palabras clave: metagenómica, enzima esterasa, caracterización, suelos, Lipasa/esterasa

A reversible luminescent quinoline based chemosensor for recognition of Zn2+ ions in aqueous methanol medium and its logic gate behavior

A new Schiff-base receptor HL, based on 8-aminoquinoline and 2-imidazole carboxaldehyde has been investigated as a selective and sensitive reversible luminescent chemosensor for Zn2+ ions in aqueous methanol with detection limit in micromolar range. The fluorescence competition and ratiometric analysis were carried out in presence of various metal ions to confirm the selectivity of HL towards Zn2+ ions. The ‘turn-on’ fluorescence response for Zn2+ may be induced by the inhibition of C=N isomerization in HL–Zn2+. The binding property of HL with Zn2+ was examined by UV–vis and fluorescence studies. In presence of Zn2+, HL also exhibits reversible fluorescence change with EDTA and thus offers an interesting property of molecular ‘INHIBIT’ logic gate with Zn2+ and EDTA as chemical inputs. The potential utility of HL in sensing Zn2+ was also checked for real samples.

Burkholderia multivorans SB6 Lipase as a Detergent Ingredient: Characterization and Stabilization

AbstractIn this study, 265 bacterial isolates were collected from kitchen wastewater samples using Rhodamine B agar medium. Of these, 115 isolates were found to respond positively to the addition of commercial detergents. Using 16S rRNA sequence analysis, the isolate demonstrating the high stability towards commercial detergents was identified as Burkholderia multivorans. An SB6 lipase with a molecular mass of 70 kDa was purified from B. multivorans. The purified enzyme showed optimal activity at pH 9.0 and 40 °C and remained stable in the presence of various metal ions, surfactants, and oxidizing agents. The addition of boron compounds improved the pH stability and thermostability of the enzyme, which displayed stability against some commercial detergents; moreover, this stability increased when boron compounds were added to the incubation medium as stabilizers. These properties make SB6 lipase an ideal choice as an additive in detergent formulations.

Study on sorption of Cs from aqueous solution by microcapsules enclosing natural minerals

Zeolite, a natural mineral (Na8(AlO2)8(SiO2)40·20H2O) with an exchanger having high selectivity toward Cs, was encapsulated in a biopolymer matrices (sodium alginate, NaALG). The sorption of Cs on different microcapsules was investigated using batch methods under different conditions, such as time (1–24 h), acid (0.1–6 M HNO3), and salt concentration (0.001–1 M NaCl). Spherical and elastic granules were obtained, and the particle size of the microcapsules was about 700 μm. A relatively high sorption ratio of Cs (above 90 %) for MCs enclosing zeolite was obtained in the presence of 0.1–6 M HNO3 and 0.001–1 M NaCl solutions, with an equilibrium being attained within 5 h. The sorption isotherm of Cs followed a Langmuir-type equation. The relatively larger Kd value, 120 and 50 cm3/g, for Cs showed a selective sorption property in the presence of various metal ions under 2.5 M HNO3 and 1 M NaNO3.

A quinoline based pH sensitive ratiometric fluorescent sensor: Structure and spectroscopy

A new quinoline based hydrazone was synthesized via a condensation reaction and characterized by NMR, mass and single crystal X-ray diffraction studies. It was investigated for suitability as a reversible ratiometric fluorescent pH sensor in acidic pH region. The sensor exhibits intramolecular charge transfer (ICT) type photophysical changes upon protonation of the quinoline ring. No significant interference on emission behavior was observed in the presence of various metal ions. A new quinoline based hydrazone was established as a reversible ratiometric fluorescent pH sensor in the acidic pH region and structurally characterized by single crystal X-ray diffraction studies. It exhibits intramolecular charge transfer (ICT) type photophysical changes upon protonation of quinoline ring.

Cloning, expression and characterization of a novel GH5 exo/endoglucanase of Thermobifida halotolerans YIM 90462T by genome mining

The 1389-bp thcel5A gene, which encodes a family 5 of glycoside hydrolases (GH5), was screened from the draft genome of Thermobifida halotolerans YIM 90462(T). ThCel5A was most similar (77% identity) to a GH5 endoglucanase from Thermobifida fusca YX, followed by cellulases from Nocardiopsis dassonvillei subsp. dassonvillei DSM 43111, Nocardiopsis alba ATCC BAA-2165, and Kribbella flavida DSM 17836. The deduced amino acid sequence of ThCel5A, which consisted of 462 amino acid residues, encompassed a family 2 cellulose-binding module and a GH5 catalytic domain. Notably, ThCel5A hydrolysed soluble as well as insoluble cellulose substrates. The enzymatic hydrolysis assay showed that the activity of recombinant ThCel5A was optimized at pH 8.0 and 50°C. Moreover, it retained hydrolytic activity in the presence of various metal ions and >90% activity within the range of pH 8.0-9.0 after 30min at 50°C. These results suggested that this enzyme has considerable potential in industrial applications.

Polythiophene based fluorescent probe for copper ions with high sensitivity

ABSTRACTTwo new conjugated polymers poly{3‐({4‐[(2‐hydrazino‐2‐oxoethyl)(methyl)amino]cyclohexylidene}methyl)thiophene}(P1) and poly{3‐({4‐[(3‐hydrazino‐3‐oxopropyl)(methyl)amino]cyclohexylidene}methyl)thiophene}(P2) were synthesized, and their optical properties were investigated. P1 exhibited excellent selectivity toward Cu2+ ions in 50% water solution, the fluorescence color of P1 changed distinctly from greenyellow to colorless in the presence of Cu2+ under UV‐light, while introduction of other metal ions could not induce such significant variation. Moreover, highly sensitive detection of Cu2+ ions was demonstrated in 90% water solution. Its high metal‐chelating capability allowed Cu2+ recognition with a detection limit of 3.2 × 10−10 M. These results indicated that this kind of nonionic polymer containing multidentate ligand could be used as a highly selective and sensitive chemosensor for Cu2+ detection. The proposed binding mode of P1 with Cu2+ was supported by DFT calculation using Gaussian 03. Unlike P1, P2 showed no obvious fluorescent change in the presence of various metal ions due to its space steric hindrance resulted from N/O distribution on the side chain of P2. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42440.

Coumarin-based ‘turn-off’ fluorescent chemosensor with high selectivity for Cu2+ in aqueous solution

Coumarin-based “turn-off” fluorescent chemosensor, 3-acetoacetyl-7-diethylaminocoumarin (1), has been synthesized and structurally characterized by IR, 1H NMR and X-ray crystal structure analysis. The fluorescence behaviors in the presence of various metal ions were investigated in aqueous media. 1 Exhibits highly selective and sensitive absorbance and fluorescence sensing ability for Cu2+ over other metal ions. Addition of Cu2+ to the aqueous solution of 1 gave rise to obvious absorbance change and fluorescence quenching. Other competing ions, such as Mg2+, Ba2+, Mn2+, Fe3+, Co2+, Ni2+, Zn2+, Pb2+, Cd2+, Hg2+, induced negligible absorbance and fluorescence changes under the same conditions. The job’s plot showed that the stoichiometry between 1 and Cu2+ was estimated to be 1:1. The fluorescence intensity varied almost linearly vs. the concentration of Cu2+ (1.0–7.0μM), and the detection limit of Cu2+ was estimated to be 1.81nM, indicating that 1 can be used as “turn-off” fluorescent chemosensor to selectively detect Cu2+ in aqueous solution.

The Use of Boron Compounds for Stabilization of Lipase from Pseudomonas aeruginosa ES3 for the Detergent Industry

AbstractThis study aimed to characterize a lipase that is highly active and stable under typical washing conditions for use as a detergent ingredient by investigating the effects of various boron compounds on lipase stabilization under different conditions. In addition, the antimicrobial activity of the boron compounds used in enzyme stabilization was examined in order to obtain an effective antimicrobial detergent. A lipase‐producing bacterium was isolated from kitchen wastewater samples using Rhodamine‐B Agar medium and identified as Pseudomonas aeruginosa based on 16S rDNA sequence analysis. The ES3 lipase obtained from P. aeruginosa was purified, and the purified enzyme was found to have a molecular mass of 40 kDa. The enzyme showed optimal activity at pH 9.0–10.0 and 40 °C and remained stable in the presence of various metal ions, surfactants and oxidizing agents. Moreover, the pH stability and thermostability of the enzyme was improved by the addition of boron compounds, which, when used as stabilizers in the incubation media, also increased the stability of the enzyme towards commercial detergents. Furthermore, the enzyme displayed properties comparable with the commercial product Lipolase®, which has shown excellent stability towards various commercial detergents. Finally, boron compounds used to stabilize the lipase were found to possess antimicrobial properties, suggesting that detergents incorporating these compounds will also exhibit antimicrobial activity when washing clothes and dishes.

A highly selective fluorescent chemosensor for Hg2+ based on a squaraine–bis(rhodamine-B) derivative: Part II

Herein, we report an effective strategy based on coordination-induced signaling by introducing a rhodamine B group linkage into squaraine–diamine dyads as a reversible switch. The optimized design, synthesis and application of a new optical squaraine–bis(rhodamine-B) chemosensor (SRB) as an ‘off–on’ fluorescent probe for the detection of Hg2+ ions were investigated. SRB exhibited high selectivity toward Hg2+ in the presence of various metal ions, such as Al3+, Ag+, Co2+, Cs+, Cu2+, Fe3+, K+, Li+, Mg2+, Na+, Ni2+, Pb2+, and Zn2+, and the resulting complex [SRB–Hg2+] was investigated using UV–vis and fluorescence spectroscopy in acetonitrile (CH3CN). The ‘off–on’ fluorescence and color signal change of the probe are based on a Hg2+-triggered domino reaction that employs the open-ring form of rhodamine spirolactam to regain the conjugated system of the rhodamine skeleton. The mechanism for the opening of the rhodamine spirolactam ring induced by Hg2+ binding and the 1:1 stoichiometric structure of SRB and Hg2+ were confirmed using a Job's plot estimation, optical titration and FT-IR. Subsequently, a SRB–Hg2+ complex chemosensor was employed to detect CN− in the presence of different anions, such as Br−, CH3COO− or AcO−, Cl−, ClO4−, F−, HPO4−, HSO4−, I−, N3−, NO3−, PF6− and SCN−, in acetonitrile. In addition, this sensor exhibited highly selective and sensitive recognition of cyanide ions upon the addition of Hg2+ with a color change back to colorless in the same solution. Finally, SRB was successfully applied with the PEGDMA polymer to sense Hg2+ ions, which was analyzed using fluorescence confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) images.

Electrochemical Studies for Cation Recognition with Diazo-Coupled Calix[4]arenes.

The electrochemical properties of diazophenylcalix[4]arenes bearing ortho-carboxyl group (o-CAC) and ortho-ester group (o-EAC), respectively, in the presence of various metal ions were investigated by voltammetry in CH3CN. o-CAC and o-EAC showed voltammetric changes toward divalent metal ions and no significant changes with monovalent alkali metal ions. However, o-CAC preferentially binds with alkaline earth and transition metal ions, whereas no significant changes in voltammetric signals are observed in o-EAC with alkaline earth metal ions. o-EAC only binds with other transition metal ions. This can be explained on metal ion complexation-induced release of proton from the azophenol to the quinone-hydrazone tautomer followed by internal complexation of the metal ion with aid of nitrogen atoms and ortho-carbonyl groups in the diazophenylazocalix[4]arenes.

Degradation of poly(ε-caprolactone) (PCL) by a newly isolated Brevundimonas sp. strain MRL-AN1 from soil.

A poly(ε-caprolactone) (PCL)-degrading bacterium designated as strain MRL-AN1 was isolated from soil. The bacterium was identified as Brevundimonas sp. strain MRL-AN1 through biochemical tests and 16S rRNA gene sequencing. Scanning electron microscopy and Fourier transform infrared spectroscopy results confirmed the degradation of PCL by strain MRL-AN1. An extracellular PCL depolymerase was purified to homogeneity by column chromatography and molecular weight was estimated to be approximately 63.49 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. PCL depolymerase could degrade not only PCL but also other aliphatic polyesters. The enzyme was stable at wide range of temperature (20-45°C) and pH (5-9) as well as stable in the presence of various metal ions, surfactants and organic solvents. Phenylmethylsulfonyl fluoride inhibited enzyme activity that indicates this enzyme belongs to the serine hydrolase family. It is concluded from the results that the enzymes from strain MRL-AN1 might be applied in the process of biochemical monomer recycling in the polyester-contaminated environments.

Degradation of poly(ε-caprolactone) by a thermophilic bacterium Ralstonia sp. strain MRL-TL isolated from hot spring

A thermophilic bacterium, designated as strain MRL-TL was isolated from hot water spring that could degrade poly(ε-caprolactone) (PCL). The bacterium was identified as Ralstonia sp. strain MRL-TL by 16S rRNA gene sequencing. The results of scanning electron microscopy (SEM) and fourier transform infra-red (FTIR) spectroscopy indicated the degradation of PCL by strain MRL-TL. The degradation of PCL in nature is attributed to microorganisms that secrete extracellular PCL depolymerases. PCL depolymerase was purified to homogeneity by column chromatography, as indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and molecular weight was found to be approximately 50 kDa. The enzyme preferred substrate among p-nitrophenyl acyl esters was p-NP-caproate (C6), indicating that the enzyme is an esterase rather than a lipase. The enzyme was stable at 37 °C–55 °C (with an optimal temperature 50 °C) and in a pH range of 6.0–8.0 (with an optimal pH of 7.0). It was stable in the presence of various metal ions, inhibitors and surfactants. Phenylmethyl sulphonyl fluoride (PMSF) inhibited enzyme activity, which indicates that this enzyme belongs to the serine hydrolase family like other PHA depolymerases. The enzymes from MRL-TL could degrade various aliphatic polyesters; therefore, it might be applied for bioremediation in the polyesters-contaminated environments.

Analyte interactions with a new ditopic dansylamide-nitrobenzoxadiazole dyad: a combined photophysical, NMR, and theoretical (DFT) study.

We report herein the synthesis and photophysical studies on a new multicomponent chemosensor dyad comprising two fluorescing units, dansylamide (DANS) and nitrobenzoxadiazole (NBD). The system has been developed to investigate receptor-analyte binding interactions in the presence of both cations and anions in a single molecular system. A dimethyl amino (in the DANS unit) group is used as a receptor for cations, and acidic hydrogens of sulfonamide and the NBD group are used as receptors for anions. The system is characterized by conventional analytical techniques. The photophysical properties of this supramolecular system in the absence and presence of various metal ions and nonmetal ions as additives are investigated in an acetonitrile medium. Utility of this system in an aqueous medium has also been demonstrated. The absorption and fluorescence spectrum of the molecular system consists of a broad band typical of an intramolecular charge-transfer (ICT) transition. A low quantum yield and lifetime of the NBD moiety in the present dyad indicates photoinduced electron transfer (PET) between DANS and the NBD moiety. The fluorescence intensity of the system is found to decrease in the presence of fluoride and acetate anions; however, the quenching is found to be much higher for fluoride. This quenching behavior is attributed to the enhanced PET from the anion receptor to the fluorophore moiety. The mechanistic aspect of the fluoride ion signaling behavior has also been studied by infrared (IR) and (1)H NMR experiments. The hydrogen bonding interaction between the acidic NH protons of the DPN moiety and F(-) is found to be primarily responsible for the fluoride selective signaling behavior. While investigating the cation signaling behavior, contrary to anions, significant fluorescence enhancement has been observed only in the presence of transition-metal ions. This behavior is rationalized by considering the disruption of PET communication between DANS and the NBD moiety due to transition-metal ion binding. Theoretical (density functional theory) studies are also performed for the better understanding of the receptor-analyte interaction. Interestingly, negative cooperativity in binding is observed when the interaction of this system is studied in the presence of both Zn(2+) and F(-). Fluorescence microscopy studies also revealed that the newly developed fluorescent sensor system can be employed as an imaging probe in live cells.

Purification and characterization of a cold-adapted pullulanase from a psychrophilic bacterial isolate.

There is a considerable potential of cold-active biocatalysts for versatile industrial applications. A psychrophilic bacterial strain, Shewanella arctica 40-3, has been isolated from arctic sea ice and was shown to exhibit pullulan-degrading activity. Purification of a monomeric, 150-kDa pullulanase was achieved using a five-step purification approach. The native enzyme was purified 50.0-fold to a final specific activity of 3.0 U/mg. The enzyme was active at a broad range of temperature (10-50 °C) and pH (5-9). Optimal activity was determined at 45 °C and pH 7. The presence of various metal ions is tolerated by the pullulanase, while detergents resulted in decreased activity. Complete conversion of pullulan to maltotriose as the sole product and N-terminal amino acid sequence indicated that the enzyme is a type-I pullulanase and belongs to rarely characterized pullulan-degrading enzymes from psychrophiles.

ICT based ratiometric fluorescent pH sensing using quinoline hydrazones

Two new quinoline hydrazones were synthesized, characterized and investigated as reversible ratiometric fluorescence pH sensors in the acidic pH region. The sensors were designed by the formation of simple donor–acceptor couple of quinoline aldehyde and phenyl hydrazine where protonation of quinoline-N triggered the pH sensing. No significant interference on emission behavior was observed in the presence of various metal ions. The sensors were used to visualize HeLa cells both at acidic and neutral pH with different emission. The MTT assay revealed negligible toxicity for both the hydrazones. The spectral properties, especially the large Stokes shift and the geometry of the molecules at the ground and excited states had been rationalized through DFT and TDDFT studies.

Hydrazone based luminescent receptors for fluorescent sensing of Cu2+: Structure and spectroscopy

Two new luminescent hydrazones, HL1 and HL2 were investigated for selective and sensitive fluorescent recognition of Cu2+ in aqueous medium (CH3CN/H2O (1:4, v/v) solvent system) with a 1:1 binding stoichiometry. The emission peak of HL (λem=405nm), undergoes significant quenching upon complexation with Cu2+. The quantum yields for the receptors and in situ formed Cu2+ complexes were determined. The absorption ratiometric analysis was carried out in presence of various metal ions to confirm the selectivity of the receptors towards Cu2+. They were able to detect Cu2+ with a ~0.9µM detection limit as indicated by fluorimetric measurements. The molecular structures of the receptors were determined by single crystal X-ray diffraction analysis.

Fluorescent Au(I)@Ag₂/Ag₃ giant cluster for selective sensing of mercury(II) ion.

Highly stable Au(I)(core)-Ag(0)(shell) particles have been synthesized in aqueous solution via a green chemistry pathway utilising sunlight irradiation. The shell of the particles is composed of fluorescent Ag2 and Ag3 clusters which make the large core-shell particles highly fluorescent. The Au(I) core of the particles offers long-term stability to the silver clusters, which are otherwise unstable in solution at room temperature, by the transfer of electron density from the shell. Successive additions of Hg(II) ions to the fluorescent solution cause efficient and selective quenching of the fluorescence with gradual red shifting of the emission peak. The metallophilic 5d(10)(Hg(2+))-4d(10)(Ag(δ+)) interaction as well as Hg(II) stimulated aggregation have been ascribed to causing the fluorescence quenching and red shift. The fluorescent Au(I)(core)-Ag(0)(shell) particles are a highly selective and sensitive sensing platform for the detection of Hg(II) down to 6 nM in the presence of various metal ions. The detection limit is far below the permissible level as determined by the EPA. Interferences due to Cu(II) and Fe(III) have been eliminated using Na2-EDTA and NH4HF2, respectively. The fluorescent particles are successfully transferred to various solvent systems making Hg(II) determination also possible in non-aqueous media. Finally, the temperature dependent fluorescence change with and without Hg(II) provides information about the metallophilic interaction.

Biochemical properties of a new cold-active mono- and diacylglycerol lipase from marine member Janibacter sp. strain HTCC2649.

Mono- and di-acylglycerol lipase has been applied to industrial usage in oil modification for its special substrate selectivity. Until now, the reported mono- and di-acylglycerol lipases from microorganism are limited, and there is no report on the mono- and di-acylglycerol lipase from bacteria. A predicted lipase (named MAJ1) from marine Janibacter sp. strain HTCC2649 was purified and biochemical characterized. MAJ1 was clustered in the family I.7 of esterase/lipase. The optimum activity of the purified MAJ1 occurred at pH 7.0 and 30 °C. The enzyme retained 50% of the optimum activity at 5 °C, indicating that MAJ1 is a cold-active lipase. The enzyme activity was stable in the presence of various metal ions, and inhibited in EDTA. MAJ1 was resistant to detergents. MAJ1 preferentially hydrolyzed mono- and di-acylglycerols, but did not show activity to triacylglycerols of camellia oil substrates. Further, MAJ1 is low homologous to that of the reported fungal diacylglycerol lipases, including Malassezia globosa lipase 1 (SMG1), Penicillium camembertii lipase U-150 (PCL), and Aspergillus oryzae lipase (AOL). Thus, we identified a novel cold-active bacterial lipase with a sn-1/3 preference towards mono- and di-acylglycerides for the first time. Moreover, it has the potential, in oil modification, for special substrate selectivity.