scholarly journals Impact of Sinorhizobium meliloti Exopolysaccharide on Adsorption and Aggregation in the Copper(II) Ions/Supporting Electrolyte/Kaolinite System

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1950
Author(s):  
Katarzyna Szewczuk-Karpisz ◽  
Agnieszka Tomczyk ◽  
Iwona Komaniecka ◽  
Adam Choma ◽  
Agnieszka Adamczuk ◽  
...  
Keyword(s):  
Soil Bacteria ◽  
Sinorhizobium Meliloti ◽  
Supporting Electrolyte ◽  
Polymer Concentration ◽  
Mixed System ◽  
Soil Bioremediation ◽  
Adsorbed Amount ◽  
Physicochemical Interactions ◽  
Pseudo Second Order ◽  
Insight Into

To obtain insight into physicochemical interactions between Cu(II) ions, kaolinite, and exopolysaccharide (EPS) synthesized by Sinorhizobium meliloti Rm 1021 soil bacteria, an adsorption, electrokinetic, and aggregation study was performed in the selected systems. The obtained data showed that supporting electrolyte type affects both EPS and Cu(II) ions adsorption. For initial Cu(II) concentration 100 mg/L, 4.36 ± 0.25 mg/g (21.80 ± 1.00%) of the ions were adsorbed in 0.001 M NaCl and 3.76 ± 0.20 mg/g (18.80 ± 1.00%) in 0.001 M CaCl2. The experimental data were best fitted to the Langmuir model as well as pseudo second-order equation. The EPS adsorbed amount on kaolinite was higher in the CaCl2 electrolyte than in NaCl one. For an initial polymer concentration of 100 mg/L, the EPS adsorbed amount was 4.69 ± 0.08 mg/g (23.45 ± 0.40%) in 0.001 M NaCl and 5.26 ± 0.15 mg/g (26.32 ± 0.75%) in 0.001 M CaCl2. In the mixed system, regardless of electrolyte type, exopolysaccharide contributed to immobilization of higher amount of copper(II) ions on the clay mineral. Also, in the samples containing heavy metal ions and exopolysaccharide simultaneously, the aggregation of kaolinite particles was the strongest. The results presented in the paper may be very helpful in soil bioremediation, especially in the development of technologies reducing the mobility of heavy metals in the environment.

Selective Sensing Platform Utilizing Graphitized Multi-Walled Carbon Nanotubes for Monitoring of Ondansetron and Paracetamol

2020 ◽  
Vol 16 ◽  
Author(s):  
Biljana Nigović ◽  
Iva Šimunić ◽  
Ana Mornar
Keyword(s):  
Carbon Nanotubes ◽  
Cation Exchange ◽  
Supporting Electrolyte ◽  
Polymer Concentration ◽  
Fixed Dose ◽  
Sensing Platform ◽  
Multi Walled Carbon Nanotubes ◽  
Electroanalytical Method ◽  
Walled Carbon Nanotubes

Background: Ondansetron and paracetamol are often co-administrated to prevent and treat nausea and vomiting caused by anaesthesia and to control of postoperative pain. In addition, ondansetron is used as the first-line antiemetic in paracetamol overdose. Therefore, selective and sensitive method for their simultaneous analysis is of a great importance. The electroanalytical methods are highly sensitive and offer many possibilities for new sensor platform design. However, at present, no electroanalytical method for simultaneous determination of these drugs has been proposed. Objective: The aim of this study was to develop a novel nanosensor for selective monitoring of ondansetron and paracetamol in pharmaceutical and biological samples without expensive and time-consuming pretreatments. Methods: The graphitized multi-walled carbon nanotubes embedded in a cation exchange polymer matrix was selected, among various surface functionalizations evaluated, to design novel sensor. Based on its excellent sensing performance, the first electroanalytical method was developed for rapid concurrent determination of investigated drugs. Results: The scanning electron microscopy study showed interlinked nanoporous network structure and highly enlarged active surface. The developed sensor facilitated electron transfer in the oxidation of both drugs and tremendously enhanced the adsorption capacity for ondasetron, thus exhibiting significant increase of drug responses and sensitivity. To obtain much sensitive response of investigated drugs the effect of pH values of supporting electrolyte, dispersed nanomaterial amount, the cation exchange polymer concentration, drop-casting volume of nanocomposite suspension, accumulation potential and deposition time on the peak current was evaluated. The developed electroanalytical method was validated and practical utility of the proposed nanosensor was tested. Conclusion: The developed sensor is promising sensing platform with a fast response time for analysis of ondansetron and paracetamol at very different concentration levels found in their fixed-dose combination and human serum sample after recommended daily doses showing its potential usage in pharmaceutical quality control and clinical research.

scholarly journals Unearthing the Boreal Soil Resistome Associated with Permafrost Thaw

2020 ◽  
Author(s):  
Tracie J. Haan ◽  
Devin M. Drown
Keyword(s):  
Antibiotic Resistance ◽  
Active Layer ◽  
Resistance Genes ◽  
Soil Bacteria ◽  
Bacterial Community Composition ◽  
Ecological Niches ◽  
Whole Genome ◽  
Near Surface ◽  
Permafrost Thaw ◽  
Insight Into

ABSTRACTUnderstanding the distribution and mobility of antibiotic resistance genes (ARGs) in soil bacteria from diverse ecological niches is critical in assessing their impacts on the global spread of antibiotic resistance. In permafrost associated soils, climate and human driven forces augment near-surface thaw altering the overlying active layer. Physiochemical changes shift bacterial community composition and metabolic functioning, however, it is unknown if permafrost thaw will affect ARGs comprising the boreal soil resistome. To assess how thaw shifts the resistome, we performed susceptibility testing and whole genome sequencing on soil isolates from a disturbance-induced thaw gradient in Interior Alaska. We found resistance was widespread in the Alaskan isolates, with 87% of the 90 isolates resistant to at least one of the five antibiotics. We also observed positive trends in both the proportion of resistant isolates and the abundance of ARGs with permafrost thaw. However, the number of ARGs per genome and types of genes present were shown to cluster more strongly by bacterial taxa rather than thaw emphasizing the evolutionary origins of resistance and the role vertical gene transfer has in shaping the predominantly chromosomally encoded ARGs. The observed higher proportion of plasmid-borne and distinct ARGs in our isolates compared to RefSoil+ suggests local conditions affect the composition of the resistome along with selection for ARG mobility. Overall taxonomy and geography shape the resistome, suggesting that as microbial communities shift in response to permafrost thaw so will the ARGs in the boreal active layer.IMPORTANCEAs antibiotic resistance continues to emerge and rapidly spread in clinical settings, it is imperative to generate studies that build insight into the ecology of environmental resistance genes that pose a threat to human health. This study provides insight into the occurrence of diverse ARGs found in Alaskan soil bacteria which is suggestive of the potential to compromise health. The observed differences in ARG abundance with increasing permafrost thaw suggest the role of soil disturbance in driving the distribution of resistant determinants and the predominant taxa that shape the resistome. Moreover, the high-quality whole genome assemblies generated in this study are an extensive resource for microbial researchers interested in permafrost thaw and will provide a steppingstone for future research into ARG mobility and transmission risks.

Effect of Process Parameters on Jet Length in Electrospraying of Thermoplastic Polymer

2012 ◽  
Vol 535-537 ◽  
pp. 1146-1150 ◽  
Author(s):  
Amit Jadhav ◽  
Li Jing Wang ◽  
Carl Lawrence ◽  
Rajiv Padhye
Keyword(s):  
Polymer Solution ◽  
Process Parameters ◽  
Thermoplastic Polyurethane ◽  
Polymer Concentration ◽  
Spray Angle ◽  
Thermoplastic Polymer ◽  
Coating Quality ◽  
Jet Length ◽  
Series Of Experiments ◽  
Insight Into

Electrospraying is inexpensive and an effective way to produce submicron range coating. Spray Angle and Jet Length are important characteristics that affect coating quality while polymer solution subjected to electrospraying. It was of interest to determine the effect of the process parameters on Jet Length. In this paper, an attempt was made to apply the electrospraying concept for coating textile surfaces. Series of experiments were carried out employing different settings of process parameters such as voltage, nozzle-collector distance and polymer concentration. Thermoplastic polyurethane dissolved in tetrahydrofluran was used as a solution. The results provide some insight into the effect of electrospraying process parameters on Jet Length

Do Exudates Affect Cadmium Speciation and Bioavailability to the Rhizobacterium Sinorhizobium meliloti?

2006 ◽  
Vol 3 (6) ◽  
pp. 424 ◽  
Author(s):  
Karine Dedieu ◽  
Tatiana Iuranova ◽  
Vera I. Slaveykova
Keyword(s):  
Soil Bacteria ◽  
Sinorhizobium Meliloti ◽  
Ion Concentration ◽  
Nutrient Cycles ◽  
Free Concentration ◽  
Soil Solutions ◽  
Constitutive Process ◽  
Free Ion ◽  
Cadmium Speciation

Environmental Context. Heavy metals such as cadmium can affect soil microbes and consequently perturb important nutrient cycles resulting in deterioration of the soil fertility. Conversely, soil bacteria might influence cadmium cycling, bioavailability and ecotoxicity by producing exudates such as proteins, polysaccharides and siderophores. These substances are shown to form complexes with cadmium, decreasing the free concentration of cadmium in soil solutions. Abstract. To better understand the role of exudates in cadmium (Cd) speciation and biouptake by the bacterium Sinorhizobium meliloti, the content of various exudate components, including siderophores, proteins and polysaccharides, was quantified in the absence and presence of 10 μM Cd at pH 5.0 and pH 7.0. The obtained results demonstrate that the release of exudates by S. meliloti is a constitutive process rather than one induced by the presence of Cd. Nonetheless, exudates complex Cd and significantly reduce its free ion concentration. Cd bioavailability to S. meliloti was characterized by the amount of adsorbed and intracellular Cd. Adsorbed Cd at pH 5.0 was higher than that at pH 7.0, which is consistent with the higher free Cd concentration and lower amounts of exudates released at that pH. The observed reduction in intracellular Cd at pH 5.0 compared with pH 7.0 was attributed to the prevailing competition between protons and Cd ions for transport sites.

scholarly journals Two-Stage Adsorber Design for Methylene Blue Removal by Coconut Shell Activated Carbon

2021 ◽  
Vol 17 (6) ◽  
pp. 768-775
Author(s):  
Fadina Amran ◽  
Nur Fatiah Zainuddin ◽  
Muhammad Abbas Ahmad Zaini
Keyword(s):  
Methylene Blue ◽  
Activated Carbon ◽  
Contact Time ◽  
Coconut Shell ◽  
Two Stage ◽  
Methylene Blue Removal ◽  
Pseudo Second Order ◽  
Coconut Shell Activated Carbon ◽  
Langmuir Constants ◽  
Insight Into

The present work was aimed at evaluating the performance of two-stage adsorber for methylene blue removal by coconut shell activated carbon in minimizing the adsorbent mass and contact time. The Langmuir constants were used to evaluate the optimum mass, while the pseudo-second-order constants for contact time. Results show that the adsorbent mass can only be minimized by 0.01 % due to the high adsorbent affinity towards methylene blue, while the contact time has been optimized to 12.2 min at the studied conditions. The effect of adsorbent affinity in two-stage adsorber was analyzed to shed some light about its importance in the design of two-stage adsorber. The performance evaluation was also discussed to bring insight into wastewater treatment applications.

scholarly journals Genetic Variation of Sinorhizobium meliloti Isolates Differing in Their Ability to Drought Tolerance

2015 ◽  
Vol 9 (2) ◽  
pp. 7-22
Author(s):  
Rana A. Hameed Hameed ◽  
Nidhal N. Hussain Hussain ◽  
Abed aljasim M. Aljibouri Aljibouri
Keyword(s):  
Genetic Diversity ◽  
Cluster Analysis ◽  
Genetic Variation ◽  
Soil Bacteria ◽  
Sinorhizobium Meliloti ◽  
Forage Crop ◽  
Drought Tolerant ◽  
Rapd Pcr ◽  
Tolerance Study ◽  
Polyethylene Glycol 6000

Soil bacteria Sinorhizobium meliloti had enormous agricultural value, due to their ability infixing nitrogen symbiotically with an important forage crop legume- alfalfa. The aim of thisstudy (i) isolate indigenous S. meliloti from different field sites in Iraq, (ii) evaluate the isolatestolerance to induce drought using polyethylene glycol-6000, (iii) assessing genetic diversity andgenetic relationships among isolates of natural population with drought tolerant abilities.Drought tolerance study revealed vast variations between Sinorhizobium isolates, the highesttolerant isolates to drought were twelve from total thirty 40%, tolerated from -3 up to -4 Mpa(mega pascal), while the drought sensitive isolates tolerated upto – 1.5 Mpa, except isolate Bs58which tolerated upto -1 Mpa water potential. The growth declined with the increase of droughtstress. Cluster analysis based on RAPD-PCR showed significant differences among S. melilotiisolates, and the results gave almost identical grouping of isolates in regards to droughtexperiment. Among indigenous isolates two divergent groups could be determined, the first majorgroup included drought tolerant isolates and the second major group comprised all droughtmoderate and sensitive isolates with 40% similarity between the two major groups.

scholarly journals Aggregation by depletion attraction in cultures of bacteria producing exopolysaccharide

2012 ◽  
Vol 9 (77) ◽  
pp. 3490-3502 ◽  
Author(s):  
Gary Dorken ◽  
Gail P. Ferguson ◽  
Chris E. French ◽  
Wilson C. K. Poon
Keyword(s):  
Phase Separation ◽  
Growth Medium ◽  
Sinorhizobium Meliloti ◽  
Cell Concentration ◽  
Polymer Concentration ◽  
Colloidal Dispersions ◽  
Phase Behaviour ◽  
Self Organization ◽  
Form Part ◽  
Small Clusters

In bacteria, the production of exopolysaccharides—polysaccharides secreted by the cells into their growth medium—is integral to the formation of aggregates and biofilms. These exopolysaccharides often form part of a matrix that holds the cells together. Investigating the bacterium Sinorhizobium meliloti , we found that a mutant that overproduces the exopolysaccharide succinoglycan showed enhanced aggregation, resulting in phase separation of the cultures. However, the aggregates did not appear to be covered in polysaccharides. Succinoglycan purified from cultures was applied to different concentrations of cells, and observation of the phase behaviour showed that the limiting polymer concentration for aggregation and phase separation to occur decreased with increasing cell concentration, suggesting a ‘crowding mechanism’ was occurring. We suggest that, as found in colloidal dispersions, the presence of a non-adsorbing polymer in the form of the exopolysaccharide succinoglycan drives aggregation of S. meliloti by depletion attraction. This force leads to self-organization of the bacteria into small clusters of laterally aligned cells, and, furthermore, leads to aggregates clustering into biofilm-like structures on a surface.

scholarly journals The rkp-1 Cluster Is Required for Secretion of Kdo Homopolymeric Capsular Polysaccharide in Sinorhizobium meliloti Strain Rm1021

2009 ◽  
Vol 191 (22) ◽  
pp. 6988-7000 ◽  
Author(s):  
Maike G. Müller ◽  
Lennart S. Forsberg ◽  
David H. Keating
Keyword(s):  
Soil Bacteria ◽  
Sinorhizobium Meliloti ◽  
Capsular Polysaccharide ◽  
Root Nodules ◽  
Nitrogen Stress ◽  
Capsular Polysaccharides ◽  
Leguminous Plants ◽  
Endosymbiotic Bacteria ◽  
Meliloti Strain ◽  
Intracellular Polysaccharide

ABSTRACT Under conditions of nitrogen stress, leguminous plants form symbioses with soil bacteria called rhizobia. This partnership results in the development of structures called root nodules, in which differentiated endosymbiotic bacteria reduce molecular dinitrogen for the host. The establishment of rhizobium-legume symbioses requires the bacterial synthesis of oligosaccharides, exopolysaccharides, and capsular polysaccharides. Previous studies suggested that the 3-deoxy-d-manno-oct-2-ulopyranosonic acid (Kdo) homopolymeric capsular polysaccharide produced by strain Sinorhizobium meliloti Rm1021 contributes to symbiosis with Medicago sativa under some conditions. However, a conclusive symbiotic role for this polysaccharide could not be determined due to a lack of mutants affecting its synthesis. In this study, we have further characterized the synthesis, secretion, and symbiotic function of the Kdo homopolymeric capsule. We showed that mutants lacking the enigmatic rkp-1 gene cluster fail to display the Kdo capsule on the cell surface but accumulate an intracellular polysaccharide of unusually high M r. In addition, we have demonstrated that mutations in kdsB2, smb20804, and smb20805 affect the polymerization of the Kdo homopolymeric capsule. Our studies also suggest a role for the capsular polysaccharide in symbiosis. Previous reports have shown that the overexpression of rkpZ from strain Rm41 allows for the symbiosis of exoY mutants of Rm1021 that are unable to produce the exopolysaccharide succinoglycan. Our results demonstrate that mutations in the rkp-1 cluster prevent this phenotypic suppression of exoY mutants, although mutations in kdsB2, smb20804, and smb20805 have no effect.

Soil bacteria and protists show different sensitivity to polycyclic aromatic hydrocarbons at controlled chemical activity

2019 ◽  
Vol 366 (17) ◽  
Author(s):  
Anne Winding ◽  
Jakub Jan Modrzyński ◽  
Jan H Christensen ◽  
Kristian K Brandt ◽  
Philipp Mayer
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Growth Inhibition ◽  
Exposure Time ◽  
Aromatic Hydrocarbons ◽  
Soil Bacteria ◽  
Sinorhizobium Meliloti ◽  
Single Species ◽  
Chemical Activity ◽  
Food Web Structure ◽  
Polycyclic Aromatic

ABSTRACT This study linked growth inhibition of soil bacteria and protists to the chemical activity (a) of polycyclic aromatic hydrocarbons (PAHs) and compared the sensitivities of bacteria and protists. Passive dosing from pre-loaded silicone provided well-defined and constant a of PAHs in independent tests. Single-species growth inhibition with two bacterial (Pseuodomonas fluorescens DR54 and Sinorhizobium meliloti) and two protist (Cercomonas longicauda and Acanthamoeba castellanii) strains at maximum a (amax) of nine and four PAHs, respectively, showed no inhibition of PAHs with amax below 0.1 (pyrene and anthracene), while growth inhibition was observed for PAHs with amax above 0.1 (e.g. fluorene, fluoranthene and naphthalene). The bacteria were less sensitive than the protists. Soil bacterial community-level growth inhibition by naphthalene was in good agreement with single-species data, but also indicated the presence of sensitive bacteria that were inhibited by a below 0.05 and increasing pre-exposure time giving higher inhibition. The a of 50% inhibition (Ea50) was 0.434 and 0.329 for 0.5 and 4 h pre-exposure time, respectively. Invertebrates tended to be more sensitive than single-celled organisms tested here. This suggests that PAH exposure leads to differential toxicity in soil biota, which may affect soil food web structure and cycling of organic matter.

scholarly journals Anionic polyacrylamide influence on the lead(II) ion accumulation in soil – the study on montmorillonite

2020 ◽  
Vol 18 (2) ◽  
pp. 599-607
Author(s):  
G. Fijałkowska ◽  
K. Szewczuk-Karpisz ◽  
M. Wiśniewska
Keyword(s):  
Heavy Metal ◽  
Polymer Concentration ◽  
Heavy Metal Accumulation ◽  
Ion Concentration ◽  
Anionic Polymer ◽  
Electrokinetic Properties ◽  
Polymer Addition ◽  
Adsorbed Amount ◽  
Carboxylic Groups ◽  
Anionic Polyacrylamide

Abstract Purpose Polymeric substances, as soil conditioners, limit the erosion process as well as improve the soil structure. The same macromolecular compounds may influence the heavy metal accumulation in soil environment. The main aim of this study was investigation of anionic polyacrylamide (AN PAM) effect on the lead(II) ion sorption on the montmorillonite surface. The effects of Pb(II) ion concentration, sequence of heavy metal and anionic polymer addition into the system as well as anionic group content in the PAM macromolecules were also studied. Materials and methods The study was performed on montmorillonite (clay mineral). Two types of polymers were used: AN PAM 5% and AN PAM 30% containing 5% and 30% of carboxylic groups, respectively. The adsorbed amounts of Pb(II) ions or AN PAM on the solid were determined spectrophotometrically. Electrokinetic properties of the examined systems were established using potentiometric titration and microelectrophoresis method. The montmorillonite aggregation without and with selected substances was described based on the sedimentation study. Results At pH 5 the Pb(II) adsorbed amount on montmorillonite equaled 0.05 mg/m2 (for the initial concentration 10 ppm). Anionic polyacrylamide increased this value significantly (it was 0.11 mg/m2 with AN PAM 5% and 0.11 mg/m2 with AN PAM 30%). The lead(II) ions presence causes a slight increase of the anionic PAM adsorption on the montmorillonite surface. For example, for the initial polymer concentration 100 ppm, the AN PAM 5% adsorbed amount without Pb(II) equaled 0.49 mg/m2, whereas with Pb(II) – 0.57 mg/m2. What is more, anionic polyacrylamide and lead(II) ions affected electrokinetic properties and stability of the montmorillonite suspension. Conclusions Anionic polyacrylamide makes the Pb(II) accumulation on the montmorillonite surface larger and, as a consequence, reduces the Pb(II) availability to organisms. Therefore, this macromolecular compound can certainly be used to remediate soils contaminated with heavy metals.

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