Increase In Metal Ion Concentration Research Articles

Comparative Spectrophotometric Determination of Neodymium (III), Praseodymium (III), Samarium (III) and Terbium (III) in Aqueous and Micelle Media

This research work titled comparative spectrophotometric determination of neodymium (III), praseodymium (III), samarium (III) and terbium (III)in aqueous and micelle media using schiff base was carried out with the aim to use a simple, rapid and sensitive spectrophotometric method for the determination of Nd (III), Pr (III), Sm(III) and Tb(III) using the Schiff base 2,2′-((1E,1′E)-(1,2-phenylenebis(azanlylidene)bis (methanylylidene))diphenol (BSOPD) as a ligand. Spectral and absorbance measurements were carried out using UV/Visible Spectrophotometer (Jenway model no.: 6305) with 1-cm matched quartz cells. This method of experiment was based on the formation of green coloured complexes, upon the reaction of Nd(III) and Pr(III) and a brown coloured complexes for Sm(III) and Tb(III) having a maximum absorbance of 376, 386, 384 and 380 nm respectively. The comparative analysis of the complexes formed in aqueous and in micellar media were investigated in this study. In the obtained results, it was discovered that, Beer’s law was obeyed in the concentration ranges of 0.001 - 0.02 ppm. The molar absorptivity was found to be in the range of 7,776- 23,197 and 27,087 dm³mol^-1cm^-1 and the Sandell’s sensitivity for the compounds analyzed were in the ranges of 6.13-19.34 g cm^-2. The increase in absorbance in the presence of the surfactants is due to micelle formation. The reactants were bound in a small volume of stern layer of the micelle leading to a greater increase in concentration effect. This effect in concentration reaches a maximum before decreasing due to dilution effect occasioned by increase in metal ion concentration.

Metal-binding and folding thermodynamics of Escherichia coli ribonuclease HI related to its catalytic function

Escherichia coli ribonuclease HI (RNH) hydrolyzes the RNA strands of RNA/DNA hybrids in the presence of Mg2+ at the highest level, relative to other metal ions. The Mg2+ binding affinity was 8.39 × 103 M−1, which was lower than those of other metal ions. The low-affinity binder can express the maximum catalytic activity of RNH. The stability of RNH increased with increasing metal ion concentration, except for Zn2+. The thermodynamic origin for enhancing the stability of RNH with Mg2+ was more favorable entropy compared to those with other metal ions, indicating that Mg2+ binding changes the RNH structure while maintaining flexibility. Upon H124A mutation, the metal ion binding affinities decreased for Mn2+ and Zn2+ to a relatively large extent. The present thermodynamic analyses provide information on the structural dynamics of RNH with metal ion exchangeable binding, which can reasonably explain the metal-ion-dependent catalytic activity.

A comprehensive investigation on the sorption of U(VI) and Eu(III) by polyamide microplastics: Surface-assisted microparticle formation

The sorption of Eu(ΙΙΙ) and U(VI) on microplastics (MP) has been investigated at pH 4 and increased metal ion concentrations ([Eu(ΙΙΙ)], [U(VI)] ≤ 1 mmol). The sorption studies have been carried out in batch type experiments and the characterisation of MP prior and after metal ion sorption was performed by FTIR and Raman, and Fluorescence (FS) and X-ray photoelectron (XPS) spectroscopy, ζ-potential measurements and SEM-EDS. The data clearly indicate that up to a certain concentration the metal ion sorption occurs via electrostatic interaction resulting in a surface charge neutralization and further metal ion concentration results in surface precipitation in the form of microparticles. The uranium microparticles have a well defined crystalline structure whereas in the case of europium amorphous particles are formed. The formation of microparticles on the MP surfaces is of cardinal importance regarding both, the preparation of a new type of microparticles as well as the environmental impact of such microparticle structures.

Development of high copper concentration, low operating temperature, and environmentally friendly electroless copper plating using a copper ‐ glycerin complex solution

Few researchers have studied high metal ions concentration electroless plating solutions since increasing metal ions concentration shortens the solution life considerably. Nevertheless, as the required thickness of the electroless plating film reduces gradually, the limited solution life will not be a large problem. There are no detailed studies on the influence of high copper concentration electroless copper plating solution and their composition on the plating rate and decomposition time. Therefore, this paper explores the plating characteristics of high copper concentration from a copper‐glycerin complex solution. Taguchi's approach was used to optimize the plating rate and decomposition time based on an L18 orthogonal array with six main effect parameters and three levels. Main effect response tables and plots were employed to investigate the parameter influence. The significant factors of plating rate are temperature and pH, and the concentration of copper sulfate has much influence on the decomposition time. Temperature and copper sulfate concentration are the key factors to optimize the formulation of the plating solution. The optimized results were obtained at 0.18 M copper sulfate, 0.133 M formaldehyde, 0.36 M glycerin, 3.2 × 10−5 M 2,2’-dipyridyl, 29 °C, pH = 12.8. The copper concentration was more than four times higher than the conventional electroless copper plating solution, and the critical factors of high copper concentration in the electroless copper plating solution were revealed. It was found that copper formed 1:2 complexes with glycerin at a pH value of 12.8. In addition, the surface morphology and the uniformity of the plating layer were included as well.

Magnetic Fe3O4/polypyrrole‐salicylaldehyde composite for efficient removal of Mn (VII) from aqueous solution by double‐layer adsorption

AbstractFe3O4 acted as the inner core, conducting polymer polypyrrole (PPy) was wrapped on the surface of Fe3O4, and salicylaldehyde (SA) was grafted to prepare the Fe3O4/PPy‐SA composite. Fe3O4/PPy‐SA exhibited double adsorption properties for Manganese (Mn) (VII) from aqueous solution. And the adsorption properties were systematically investigated. The influences of pH, initial metal ion concentration and temperature on the adsorption performance were measured, showing that the optimal adsorption pH is 2. Moreover, it was found that the adsorption kinetics followed the pseudo second order model, the initial adsorption rate was 46.1467 mg/g/min, and the process was controlled by the liquid film diffusion. The Langmuir adsorption isotherm model could describe the adsorption process well, and the increase of metal ion concentration and temperature was beneficial to the adsorption process. At 288.15 K, the maximum equilibrium adsorption capacity was 471.6981 mg/g. Thermodynamic parameters indicated that the adsorption process was spontaneous, endothermic, and entropy increment. Meanwhile, the cycle test results showed that the adsorbent has good cycle performance and broad application prospects.

Binding interaction between 4-Hydroxy-3-nitrocoumarin and metal ions-A spectroscopic approach

Metal ions play vital role in many biochemical and physiological functions when they are in very low concentrations and become lethal if certain limit is exceeded. Their detection even at very low concentration is very much essential. In this work we report the detection of metal ions Cu++ and Ni++ being members of environment pollutants using a coumarin derivative 4-Hydroxy-3-nitrocoumarin by absorption and emission spectroscopic methods. It is noticed that the metal ions are capable of reducing the absorbance (OD) and emission intensity of the coumarin derivative dissolved in Toluene, Dichloromethane and 1,2-Dichloroethane even at very low concentration of 10-3 M. The sample concentration is maintained at 10-5M. The OD is reduced with the increase in metal ion concentration without shift in absorption peak of 272 nm. Emission intensity is also quenched by them without shifting the emission peak which is located at 555 nm. The spectroscopic data is analyzed using Benisi-Hildebrand. Binding constant values are calculated using both absorption and emission data. The values are found to be towards higher side. Gibb’s free energy change which is an indication of spontaneity/non– spontaneity of compound–Metal ion binding is also evaluated. Gibb’s free energy suggests that the studied compound has more affinity towards metal ions and can selectively sense them.

Phase Studies and Efficient Recovery of Inorganic Metal Salts from the Microemulsion System Using a Sugar-Based Non-Ionic Surfactant

Abstract In the present work, the phase behaviour of the microemulsion system formulated by using water, organic solvent, and a sugar-based non-ionic surfactant was investigated in detail. We have used a sugar-based non-ionic surfactant for formulation of microemulsion, as it is a greener alternative for the formulation of a microemulsion system, owing to the following aspects: a) better physicochemical properties as compared to that of the conventional non-ionic surfactants, b) non-toxicity, and c) biodegradability. The extraction of heavy metal ions from the metal complexes as well as the recovery efficiency of heavy metal ions using a microemulsion system has been investigated. The maximum absorbance values of metal ions, after recovery from the metal complexes, were measured. Moreover, the UV-Visible spectrophotometric studies revealed that the absorbance increases with an increase in metal ion concentration in the aqueous phase while its value decreases with an increase in the concentration of potassium thiocyanate in the aqueous phase after the extraction of the metal ions from the metal complexes. Furthermore, it has also been evaluated that 4.0 mol/L potassium thiocyanate is the optimum concentration required for efficient recovery of 0.05 mol/L cobalt ion as well as nickel ions. The recovery efficiency of cobalt ions was found to be 97%, whereas that of nickel ions was determined to be 94% respectively. In addition to being an environmentally friendly approach, the present work is an economically viable option too, as it deals with the studies related to the extraction and efficient recovery of metal ions.

PRODUCTION OF Candida BIOMASSES FOR HEAVY METAL REMOVAL FROM WASTEWATERS

Yeasts can accumulate heavy metals and grow in acidic media. In the present study, it was shown that Candida yeasts in an aqueous solution accumulate single Cu(II) and Ni(II) cations. The effect of heavy metal ions on the specific growth rate of biomasses and the uptake of metal ions during the growth phase was investigated in a batch system. Bioaccumulation efficiency decreased with increasing metal ion concentrations at constant sucrose concentrations. Both the specific growth rate and the biomass concentration were more inhibited in the bioaccumulation media containing Ni(II) ions singly as compared with the bioaccumulation media containing Cu(II) ions singly. The maximum specific growth rate and the saturation constant of yeasts were examined with a double-reciprocal form of Monod equation. Metal uptake performance decreased from 81.68% to 46.28% with increasing Ni(II) concentration from 25 mg/L to 250 mg/L for Candida lipolytica. Candida biomasses may be an alternative way of removal of heavy metals from wastewaters and may constitute a sample to produce new biomass. The study showed that Candida yeasts can be used as economical biomass due to their metal resistance and efficient production.

Introducing a New Co-polymeric Adsorbent with Fast Sorption Rate and High Sorption Capacity in Removal of Heavy Metal Ions: a Thermodynamic and Kinetic Study

Heavy metal ions have been recognized as the most hazardous contaminants of water sources. In this study, a novel polymeric adsorbent based on 2-hydroxyethyl methacrylate (HEMA), acrylic acid (AA), and 1,4-butanediol dimethacrylate (BDDMA) was successfully synthesized and its efficiency in removal of selected heavy metal ions (Pb2+ and Cd2+) were investigated. The role of significant parameters such as pH, contact time, adsorbent dose, metal ions concentration and temperature on removing harmful metal ions were logically studied. Results showed that the amount of pH, contact time and polymer adsorbent dose had direct relation in adsorption of metal ions. While increasing metal ion concentrations have no significant effect in metal ions adsorption and that was fixed up to 15 mg/L. Adsorption isothermal process of the new polymeric adsorbent was studied by several selected models and also maximum values of adsorption capacities of the introduced adsorbent for Pb2+ and Cd2+ ions were characterized. Adsorption /desorption cycles of synthesized polymer adsorbent were around 15 times. According to the modeling of adsorption data, the pseudo-second-order kinetic equation could best describe the adsorption kinetics. According to the intra-particle diffusion studies adsorption of heavy metal ions might be dominated by external diffusion mechanism.

Metal Ions Influence on Shewanella Oneidensis MR-1 Adhesion to ITO Electrode and Enhancement Current Output

The goal in this study is to enhance the efficiency of bacterial extracellular electron transfer (EET) in Shewanella. oneidensis MR-1 by enhancing adhesion to the electrode. Our results clearly show a major difference in attachment and behavior of S. oneidensis MR-1 for Ca2+, Pb2+, Cd2+, and Mg2+ compared to the control. The final microbial coverage, as measured by confocal microscopy and cathodic peak charge in cyclic voltammetry (Qpc), increases with increasing metal ion concentrations. We found the cells attached to the electrode increased more with the addition of metal ion concentrations in the following order of metals: Ca2+ > Pb2+ > Cd2+ > Mg2+ compared to the control.Riboflavin production and glucose consumption mirrored the same order as the electrochemical results.

Blood Metal Ion Release After Primary Total Knee Arthroplasty: A Prospective Study.

ObjectivesTo investigate the course of in vivo blood metal ion levels in patients undergoing primary total knee arthroplasty (TKA) and to investigate potential risk factors associated with metal ion release in these patients.MethodsTwenty‐five patients with indication for TKA were included in this prospective study. Whole blood metal ion analysis was performed pre‐operatively and at 1 week, 6 weeks, 3 months, 6 months, and 12 months postoperatively. Clinical scores were obtained using the American Knee Society Score (AKSS) and the Oxford Knee Score (OKS) at each follow‐up and patientsʼ activity levels were assessed by measuring the mean annual walking cycles at 12 months follow‐up. Anteroposterior and lateral radiographs of the operated knee were evaluated postoperatively and at 12‐month follow‐up with regard to implant position and radiological signs of implant loosening. Correlation analysis using multivariate linear regression was performed to investigate the influence of different variables (age, gender, functional scores, number of walking cycles, and body mass index [BMI]) on blood cobalt ion concentrations.ResultsMean metal ion levels of cobalt, chromium, molybdenum, and titanium were 0.28 μg/L (SD, 0.14), 0.43 μg/L (SD, 0.49), 0.62 μg/L (SD, 0.45), and 1.96 μg/L (SD, 0.98), respectively at 12‐month follow‐up. Mean cobalt ion levels significantly increased 1‐year after surgery compared to preoperative measurements. There was no statistically significant increase of mean metal ion levels of chromium, titanium, and molybdenum at 1‐year follow‐up. Overall, metal ion levels were low and no patient demonstrated cobalt ion levels above 1 μg/L. Postoperative radiographs demonstrated well‐aligned TKAs in all patients and no signs of osteolysis or implant loosening were detected at 1‐year follow‐up. Both the AKSS and OKS significantly improved during the course of the study up to the final follow‐up. Multivariate regression analysis did not show a statistically significant correlation between the tested variables and blood cobalt ion concentrations.ConclusionA statistically significant increase of mean cobalt ion concentration at 1‐year follow‐up was found in this cohort of patients with well‐functioning TKA, although overall blood metal ion levels were relatively low. Despite low systemic metal ion concentrations seen in this cohort, the local effects of increased metal ion concentrations in the periprosthetic environment on the long‐term outcome of TKA should be further investigated.

The inflammatory pseudotumor formed after metal-on-metal hip arthroplasty

Due to its advantages of low wear, high stability and flexibility, the new generation metal-on-metal hip prosthesis is favored by many patients with hip diseases, especially young patients. However, in recent years, several studies have indicated that adverse reactions to metal debris (ARMD) caused the formation of inflammatory pseudotumor, which ultimately led to a higher revision rate after metal-on-metal hip arthroplasty. This aroused the widespread concern from doctors and patients. Moreover, revision surgery for metal-on-metal hip arthroplasty in the setting of inflammatory pseudotumor is faced with a great risk of failure because of the large defects of bone and surrounding soft tissue and difficulty in removing the original prosthesis and the fixing of the modified prosthesis. Therefore, the use of such products is restricted with caution in their choice. We summarized the recent developments in the research in the risk factors, diagnosis and treatment of inflammatory pseudotumor after metal-on-metal hip arthroplasty. The risk factors for the formation of inflammatory pseudotumor around the hip prosthesis mainly include the increase of metal ion concentration, the position of prosthesis implantation and the patient's own factors. The diagnosis mainly depends on physical examination, imaging examination, laboratory examination, arthroscopy and histological examination. The treatment strategies for clinical symptomatic and asymptomatic patients are also varies. Through the detailed analysis, evaluation and summary of the above contents, we may provide guidance for the selection of hip prosthesis, and lay the foundation for further exploration of the mechanism of inflammatory pseudotumor caused by ARMD.

Modulation of the catalytic activity of a metallonuclease by tagging with oligohistidine

Peptide tags are extensively used for affinity purification of proteins. In an optimal case, these tags can be completely removed from the purified protein by a specific protease mediated hydrolysis. However, the interactions of these tags with the target protein may also be utilized for the modulation of the protein function. Here we show that the C-terminal hexahistidine (6 × His) tag can influence the catalytic activity of the nuclease domain of the Colicin E7 metallonuclease (NColE7) used by E. coli to kill competing bacteria under stress conditions. This enzyme non-specifically cleaves the DNA that results in cytotoxicity. We have successfully cloned the genes of NColE7 protein and its R447G mutant into a modified pET-21a DNA vector fusing the affinity tag to the protein upon expression, which would be otherwise not possible in the absence of the gene of the Im7 inhibitory protein. This reflects the inhibitory effect of the 6 × His fusion tag on the nuclease activity, which proved to be a complex process via both coordinative and non-specific steric interactions. The modulatory effect of Zn2+ ion was observed in the catalytic activity experiments. The DNA cleavage ability of the 6 × His tagged enzyme was first enhanced by an increase of metal ion concentration, while high excess of Zn2+ ions caused a lower rate of the DNA cleavage. Modelling of the coordinative effect of the fusion tag by external chelators suggested ternary complex formation instead of removal of the metal ion from the active center.

Liquid-liquid extraction of Co(II) from nitrate solution using TOA

Cobalt has widespread industrial applications but if present in excess amounts it may cause several noxious effects. Liquid-liquid extraction process can be useful in cleaning the environment from harmful chemical pollutants. Solvent extraction of cobalt using cobalt nitrate as the feed solution and trioctylamine (TOA) as the extractant in toluene was carried out where the effects of nitric acid concentration, equilibration time, concentration of the extractant and cobalt ions had been investigated. The percentage extraction of Co(II) decreased upon increasing the concentration of acid. A time of 15 min was needed to achieve the extraction equilibrium. Highest percentage extraction of cobalt was achieved using 0.1 M TOA which is 99%. Cobalt loading increased with increase in metal ion concentration. Presence of nitrate ions had almost no significance in the extraction process. The loaded organic phase was stripped using different stripping agents and 99.15% back extraction was achieved with 0.1 mol/L (NH4)2CO3. The extraction mechanism was proposed from the FTIR and slope measurement.

Copper Adsorption by Magnetized Pine-Needle Biochar

The Cu(II) adsorption from aqueous solutions by magnetic biochar obtained from pine needles has been studied by means of batch-type experiments. The biochar fibers have been magnetized prior (pncm: carbonized-magnetized pine needles) and after oxidation (pncom: carbonized-oxidized-magnetized pine needles) and have been used as adsorbents to study the presence of carboxylic moieties on the magnetization and following adsorption process. The effect of pH (2–10), initial metal concentration (10−5–9·10−3 mol·L−1) and contact time (0–60 min) has been studied by varying the respective parameter, and the adsorbents have been characterized by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) measurements prior and after Cu(II)-adsorption. FTIR measurements were performed to investigate the formation of surface species and XRD measurements to record possible solid phase formation and characterize formed solids, including the evaluation of their average crystal size. The data obtained from the batch-type studies show that the oxidized magnetic biochar (pncom) presents significantly higher adsorption capacity (1.0 mmol g−1) compared to pncm (0.4 mmol g−1), which is ascribed to the synergistic effect of the carboxylic moieties present on the pncom surface, and the adsorption process follows the pseudo-second order kinetics. On the other hand, the FTIR spectra prove the formation of inner-sphere complexes and XRD diffractograms indicate Cu(II) solid phase formation at pH 6 and increased metal ion concentrations.

Photothermal-enhanced synthetic melanin inks for near-infrared imaging

Synthetic melanin has been increasingly exploited as a new class of functional ink materials due to its promising properties such as ultrahigh reflective index and blackness, and good stability in aqueous solution. Whilst the promising photothermal conversion feature of synthetic melanin has been well devoted, the relatively low near-infrared (NIR) light absorption limited their further application as the NIR imaging inks. Herein, we developed a series of synthetic melanin nanoparticles (SMNPs) inks doped with different kinds of metal ions and found that all the products exhibited enhanced light absorption ability and total photothermal effect compared to the undoped sample. Interestingly, it was also found that these properties could be improved correspondingly with the increase of metal ion concentration. This study not only provides a comprehensive understanding of the metal ion-loaded SMNPs with enhanced photothermal effect, but also paves the way towards fabricating new SMNP inks for NIR imaging applications.

Tracking metal ion-induced organic membrane fouling in nanofiltration by adopting spectroscopic methods: Observations and predictions

Natural organic matter (NOM) with the size approaching to membrane pore size is commonly considered as the crucial component leading to severe pore blocking and superfluous energy consumption. Aquatic metal ions coexisting with this NOM constituent (target NOM) exert a significant influence on membrane filtration performance; however, little work elucidated their interactions and the impacts on nanofiltration (NF). Therefore, we systematically investigated this issue by titrating three environmentally-relevant metal ions (Al3+, Fe3+ and Cu2+) into the target NOM sample obtained by pre-filtering using NF membrane. Fast spectrophotometric techniques were employed to observe the interactive performance. Results suggested that all metal ions at their critical concentrations caused severe flux decline; Cu2+ at a very low concentration of 5 μM, Al3+ and Fe3+ at 20 μM. NF performance recovered when the concentrations were beyond their critical values, and was improved at excessive concentration when flocs formed. Relationship between spectroscopic characteristics and NF performance was particularly addressed. UV–vis spectrum can be expected to be useful and predictive in membrane fouling control when Al3+ or Fe3+ presented. However, fluorescence fingerprint was not likely that effective since fluorescence intensity continuously reduced with the increasing metal ion concentration, attributed to their quenching effect on NOM fluorophores.

Metal ion binding by humic substances as emergent functions of labile supramolecular assemblies

Environmental contextThe fundamental basis for the high flexibility of humic substances is still unclear, though it is crucial for the understanding of metal bioavailability and toxicity in soil and aqueous environments. We show at the molecular level how characteristics of organic matter affect metal binding depending on the environmental conditions. Such understanding will help in the modulation of metal availability in soil and water in changing environmental situations. AbstractIn this work, we explore the hypothesis that humic substances (HS) can be perceived as labile supramolecular assemblages, the functioning of which is mainly determined by chemical composition and characteristics, the size of molecular units and weak intermolecular forces, rather than the exact primary structure of molecular moieties and their spatial configuration. To test the hypothesis, 72 computational models of three different organic mixtures were composed. The formation of inner and outer sphere metal–ligand complexes, metal binding sites, complex configurations, binding energies and aggregation/dissolution as emergent properties of HS were determined under various conditions. The results of computational modelling revealed that: (i) the highest Cu2+ binding (55.6%) was by the SRFA-22 organic model, which represents low-molecular-weight fulvic acids. In contrast, the highest amount of inner-sphere Mg–organic matter complex (63.4%) was formed in SRHA-6, which has higher-molecular-weight constituents. Therefore, a correlation between the type of cation, the system aromaticity and the extent of metal complexation is proposed. (ii) Increase of metal ion concentration and decrease of water content resulted in an increase in the number of hydrogen bonds and more compact and stable aggregates with lower hydrophilic and higher hydrophobic surface areas in SRFA-22. However, in SRHA-6, the results varied owing to the competition between metal binding, H-bonding and non-polar interactions in the structural arrangement of the aggregates. In general, the aggregation process, driven by metal complexation and water removal, resulted in the formation of more stable conformers, with lower potential energy, with the only exception of SRHA-6–Cu.

Impact of Mg2+, K+, and Na+ on rheological properties and chain conformation of soy hull soluble polysaccharide

This study aims to evaluate soy hull soluble polysaccharide fractions (SHSPs) obtained by gradient alcohol precipitation induced by Mg2+, K+, and Na+ via rheological and chain conformation analysis. The temperature sweep amplitude oscillatory-shear tests show that Mg2+, K+, and Na+ can promote gelation for SHSP20 and SHSP40, and the gel strength of SHSP20 is higher than SHSP40 at various temperatures. SHSP60 does not form gel induced by these metal ions, even at a concentration of 0.40 mol/L. In addition, atomic force microscopy further confirmed the various morphologies of these SHSP fractions induced by metal ions. SHSP20 can form a denser network structure, induced by Mg2+, K+, and Na+, than SHSP40. What's more, with the increase in metal ion concentrations, the molecular chain of SHSP60 formed aggregation, and did not form a network structure. This may be the reason why SHSP60 do not undergo a gel reaction. Furthermore, combined with rheological and atomic force microscopy results, it can be concluded that Mg2+ form a more stable and uniform network structure than K+ and Na+, which may be the reason why the gel thus formed is more resistant to temperature increase. For K+ and Na+ at the same concentration, the gel strength of SHSP20 and SHSP40 induced by Na+ is inferior to K+, because K+ induces SHSP formation as a uniform network structure, and Na+ results in an uneven form. These results suggest that SHSP fractions provided different rheological and gel properties, and can be used as ingredients in different foodstuffs.

Metal Ions Impact on <i>Shewanella Oneidensis</i> MR-1 Adhesion to ITO Electrode and the Enhancement of Current Output

The goal of this study is to enhance the efficiency of bacterial extracellular electron transfer (EET) in Shewanella oneidensis MR-1 by enhancing adhesion to the electrode surface. Our results clearly show a major difference in attachment and behavior of S. oneidensis MR-1 for Ca2+, Pb2+, Cd2+, and Mg2+ compared to the control. The final microbial coverage, as measured by confocal microscopy and cathodic peak charge in cyclic voltammetry (Qpc), increases with increasing metal ion concentrations. We found the cells attached to the electrode increased more with the addition of metal ion concentrations in the following order of metals: Ca2+ > Pb2+ > Cd2+ > Mg2+ compared to the control. The effect of metal ions on metabolism of the bacteria was tested by the riboflavin production and glucose consumption. Metabolic activity mirrored the same order of the activity as the electrochemical results.