Journal articles on the topic 'Microbial mobilisation'
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García-Aljaro, Cristina, Julia Martín-Díaz, Enric Viñas-Balada, William Calero-Cáceres, Francisco Lucena, and Anicet R. Blanch. "Mobilisation of microbial indicators, microbial source tracking markers and pathogens after rainfall events." Water Research 112 (April 2017): 248–53. http://dx.doi.org/10.1016/j.watres.2017.02.003.
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Rizoulis, Athanasios, Wafa M. Al Lawati, Richard D. Pancost, David A. Polya, Bart E. van Dongen, and Jonathan R. Lloyd. "Microbially mediated reduction of FeIII and AsV in Cambodian sediments amended with 13C-labelled hexadecane and kerogen." Environmental Chemistry 11, no. 5 (2014): 538. http://dx.doi.org/10.1071/en13238.
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Environmental context The use of groundwater with elevated concentrations of arsenic for drinking, cooking or irrigation has resulted in the worst mass poisoning in human history. This study shows that organic compounds that can be found in arsenic rich subsurface sediments may be used by indigenous microorganisms, contributing to the release of arsenic from the sediments into the groundwater. This study increases our understanding of the range of organic substrates (and their sources) that can potentially stimulate arsenic mobilisation into groundwaters. Abstract Microbial activity is generally accepted to play a critical role, with the aid of suitable organic carbon substrates, in the mobilisation of arsenic from sediments into shallow reducing groundwaters. The nature of the organic matter in natural aquifers driving the reduction of AsV to AsIII is of particular importance but is poorly understood. In this study, sediments from an arsenic rich aquifer in Cambodia were amended with two 13C-labelled organic substrates. 13C-hexadecane was used as a model for potentially bioavailable long chain n-alkanes and a 13C-kerogen analogue as a proxy for non-extractable organic matter. During anaerobic incubation for 8 weeks, significant FeIII reduction and AsIII mobilisation were observed in the biotic microcosms only, suggesting that these processes were microbially driven. Microcosms amended with 13C-hexadecane exhibited a similar extent of FeIII reduction to the non-amended microcosms, but marginally higher AsIII release. Moreover, gas chromatography–mass spectrometry analysis showed that 65% of the added 13C-hexadecane was degraded during the 8-week incubation. The degradation of 13C-hexadecane was microbially driven, as confirmed by DNA stable isotope probing (DNA-SIP). Amendment with 13C-kerogen did not enhance FeIII reduction or AsIII mobilisation, and microbial degradation of kerogen could not be confirmed conclusively by DNA-SIP fractionation or 13C incorporation in the phospholipid fatty acids. These data are, therefore, consistent with the utilisation of long chain n-alkanes (but not kerogen) as electron donors for anaerobic processes, potentially including FeIII and AsV reduction in the subsurface.
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Afolabi, Emmanuel O., Richard S. Quilliam, and David M. Oliver. "Time since faecal deposition influences mobilisation of culturable E. coli and intestinal enterococci from deer, goose and dairy cow faeces." PLOS ONE 17, no. 9 (September 2, 2022): e0274138. http://dx.doi.org/10.1371/journal.pone.0274138.
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Mobilisation is a term used to describe the supply of a pollutant from its environmental source, e.g., soil or faeces, into a hydrological transfer pathway. The overarching aim of this study was to determine, using a laboratory-based approach, whether faecal indicator bacteria (FIB) are hydrologically mobilised in different quantities from a typical agricultural, wildlife and wildfowl source, namely dairy cattle, red deer and greylag goose faeces. The mobilisation of FIB from fresh and ageing faeces under two contrasting temperatures was determined, with significant differences in the concentrations of both E. coli and intestinal enterococci lost from all faecal sources. FIB mobilisation from these faecal matrices followed the order of dairy cow > goose > deer (greatest to least, expressed as a proportion of the total FIB present). Significant changes in mobilisation rates from faecal sources over time were also recorded and this was influenced by the temperature at which the faecal material had aged over the course of the 12-day study. Characterising how indicators of waterborne pathogens are mobilised in the environment is of fundamental importance to inform models and risk assessments and develop effective strategies for reducing microbial pollution in catchment drainage waters and associated downstream impacts. Our findings add quantitative evidence to support the understanding of FIB mobilisation potential from three important faecal sources in the environment.
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Héry, Marina, Corinne Casiot, Eléonore Resongles, Zoe Gallice, Odile Bruneel, Angélique Desoeuvre, and Sophie Delpoux. "Release of arsenite, arsenate and methyl-arsenic species from streambed sediment affected by acid mine drainage: a microcosm study." Environmental Chemistry 11, no. 5 (2014): 514. http://dx.doi.org/10.1071/en13225.
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Environmental context Arsenic-rich waters generated from the oxidation of mining wastes are responsible for the severe contamination of river waters and sediments located downstream from mining sites. Under certain environmental conditions, the affected riverbed sediments may represent a reservoir for arsenic from which this toxic element may be released into water, mainly as a consequence of microbial activity. Abstract The (bio-)geochemical processes driving As mobilisation from streambed sediments affected by acid mine drainage (AMD) were investigated, and the structure of the bacterial community associated with the sediments was characterised. Microcosm experiments were set up to determine the effect of oxygen, temperature (4 and 20°C) and microbial activity on As mobilisation from contrasting sediments collected during high- (November 2011) and low- (March 2012) flow conditions in the Amous River, that received AMD. Distinct bacterial communities thrived in the two sediments, dominated by Rhodobacter spp., Polaromonas spp. and Sphingomonads. These communities included only few bacteria known for their capacity to interact directly with As, whereas biogeochemical processes appeared to control As cycling. Major As mobilisation occurred in the AsIII form at 20°C in anoxic conditions, from both November and March sediments, as the result of successive biotic reductive dissolution of Mn- and Fe-oxyhydroxides. The later process may be driven by Mn- and Fe-reducing bacteria such as Geobacter spp. and possibly occurred in combination with microbially mediated AsV reduction. The involvement of other bacteria in these redox processes is not excluded. Biomethylation occurred only with the sediments collected at low-flow during oxic and anoxic conditions, although no bacteria characterised so far for its ability to methylate As was identified. Finally, sorption equilibrium of AsV onto the sediment appeared to be the main process controlling AsV concentration in oxic conditions. Comparison with field data shows that the later process, besides biomethylation, may be of relevance to the As fate in AMD-affected streams.
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Rouwane, Asmaa, Marion Rabiet, Isabelle Bourven, Malgorzata Grybos, Lucie Mallet, and Gilles Guibaud. "Role of microbial reducing activity in antimony and arsenic release from an unpolluted wetland soil: a lab scale study using sodium azide as a microbial inhibiting agent." Environmental Chemistry 13, no. 6 (2016): 945. http://dx.doi.org/10.1071/en16029.
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Environmental contextAntimony and arsenic are toxic elements occurring naturally in the environment. We found that arsenic release to water from an unpolluted wetland soil is related to microbial reducing activity only, whereas antimony can still be released when this activity is inhibited, suggesting the involvement of additional processes. The findings show that microbial/non-microbial mechanisms control arsenic and antimony release and can thereby impact water quality at wetland outlets. AbstractIn wetland soils, the mobility of geogenic metal(loid)s is usually associated with direct or indirect microbial-induced processes (solubilisation of mineral and organic components, pH induced desorption, competition effects, dissimilatory reduction). To identify the role of microbial reducing activity in As and Sb release, we conducted two series of soil incubations (sodium azide-treated (NaN3-T) and non-treated (NT)) in closed batches for 36 days. During the incubation period, we monitored the evolution of dissolved As, Sb, Mn, FeII, organic carbon (DOC), humic substances (HS) and proteins (PN) with their apparent molecular weight distribution (aMW) as well as pH, reduction potential (Eh) and alkalinity. Results showed that the release of As and Sb occurred when microbially reducing conditions prevailed (NT soil Eh ~0mV and FeII>40mg L–1) and was inhibited for As in the absence of microbial reducing activity (NaN3-T soil; Eh>250mV and Fe<1mg L–1). In contrast, Sb behaved differently since its release was only slowed down when microbially reducing conditions were inhibited. We concluded that soil microbial reducing activity fully controls the release of As and to a lesser extent that of Sb when NaN3 is used as a microbial inhibiting agent. Since Sb release and dissolved organic matter (DOM) solubilisation (NaN3-induced artefact) occurred simultaneously in the absence of microbially reducing conditions, we concluded that organic matter could be one key factor controlling Sb mobilisation in the given conditions, which is not the case for As.
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Skoglund, Caroline, Christian Helldahl, Maria Lerm, Magnus Grenegård, Torbjörn Bengtsson, and Hanna Kälvegren. "Toll-like receptor 2 stimulation of platelets is mediated by purinergic P2X1-dependent Ca2+ mobilisation, cyclooxygenase and purinergic P2Y1 and P2Y12 receptor activation." Thrombosis and Haemostasis 103, no. 02 (2010): 398–407. http://dx.doi.org/10.1160/th09-07-0442.
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SummaryToll-like receptor 2 (TLR2), which recognise and respond to conserved microbial pathogen-associated molecular patterns, is expressed on the platelet surface. Furthermore, it has recently been shown that the TLR2/1 agonist Pam3CSK4 stimulates platelet activation. The aim of the present study was to clarify important signalling events in Pam3CSK4-induced platelet aggregation and secretion. Platelet interaction with Pam3CSK4 and the TLR2/6 agonist MALP-2 was studied by analysing aggregation, ATP-secretion, [Ca2+]i mobilisation and thromboxane B2 (TxB2) production. The results show that Pam3CSK4 but not MALP-2 induces [Ca2+]i increase, TxB2 production, dense granule secretion and platelet aggregation. Preincubation of platelets with MALP-2 inhibited the Pam3CSK4-induced responses. The ATP-secretion and aggregation in Pam3CSK4-stimulated platelets was impeded by the purinergic P2X1 inhibitor MRS 2159, the purinergic P2Y1 and P2Y12 antagonists MRS 2179 and cangrelor, the phospholipase C inhibitor U73122, the calcium chelator BAPT-AM and aspirin. The calcium mobilisation was lowered by MRS 2159, aspirin and U73122 whereas the TxB2 production was antagonised by MRS 2159, aspirin and BAPT-AM. When investigating the involvement of the myeloid differentiation factor-88 (MyD88) -dependent pathway, we found that platelets express MyD88 and interleukin 1 receptor-associated kinase (IRAK-1), which are proteins important in TLR signalling. However, Pam3CSK4 did not stimulate a rapid (within 10 minutes) phosphorylation of IRAK-1 in platelets. In conclusion, the results show that Pam3CSK4-induced platelet aggregation and secretion depends on a P2X1-mediated Ca2+ mobilisation, production of TxA2 and ADP receptor activation. The findings in this study further support a role for platelets in sensing bacterial components.
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Davies-Colley, Rob, Amanda Valois, and Juliet Milne. "Faecal contamination and visual clarity in New Zealand rivers: correlation of key variables affecting swimming suitability." Journal of Water and Health 16, no. 3 (April 11, 2018): 329–39. http://dx.doi.org/10.2166/wh.2018.214.
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Abstract Swimming is a popular activity in Aotearoa-New Zealand (NZ). Two variables that strongly influence swimming suitability of waters are faecal contamination, as indicated by the bacterium Escherichia coli, and visual clarity as it affects aesthetics and safety with respect to submerged hazards. We show that E. coli and visual clarity are inversely related overall in NZ rivers (R = −0.54), and more strongly related in many individual rivers, while similar (but positive) correlations apply also to turbidity. This finding, apparently reflecting co-mobilisation of faecal contamination and fine sediment, suggests that visual clarity, measured or estimated from appearance of submerged features, should be a valuable indicator of faecal contamination status and (more generally) swimming suitability. If swimmers were to avoid river waters <1.6 m black disc visibility (a long-established NZ guideline for swimming) they would also avoid microbial hazards (E. coli <550 cfu/100 mL about 99% of the time in NZ rivers). However, urban-affected rivers might sometimes be microbially contaminated when still clear. Water management agencies should measure visual clarity together with E. coli in river surveillance. Real-time information on swimming suitability could then be based on continuous monitoring of turbidity locally calibrated to both visual clarity and E. coli.
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Perotti, Cesare, Claudia Del Fante, Gianluca Viarengo, Marcello Maestri, and Laura Salvaneschi. "Prominin-1 Mobilisation, Collection and Immunoselection in Cancer Patients for Liver Regeneration." Blood 114, no. 22 (November 20, 2009): 2141. http://dx.doi.org/10.1182/blood.v114.22.2141.2141.
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Abstract Abstract 2141 Poster Board II-118 Background: CD133+ (Prominin-1 positive) is a 5-transmembrane glycoprotein that identifies immature progenitor stem cells. Immature hematopoietic stem cells retain the possibility to give origin to tissues different from hematopoietic cell lines (transdifferentiation). Material and methods: In this preliminary study we investigated the possibility to mobilize, collect, immunoselect and reinfuse autologous CD133+ immature stem cells in liver cancer patients. This approach was adopted to obtain, in a short time, an adequate volume increase of the disease free liver thus extending the resectability criteria of the liver, with the final goal to prolong survival. We enrolled 4 patients with a large liver cancer and no chance of resection. The mobilization protocol consisted in: G-CSF administration (10 μg/kg/day ) for 3-5 days, peripheral blood stem cell (PBSC) monitoring starting from the 3rd day, leukapheresis (LKF) collection processing 3 blood volumes when CD133+ cells>15 μL. Patients were monitored during mobilization, collection and post collection phase for clinical status, blood pressure and bleeding. Positive CD133+ immunoselection (Miltenyi Clinimacs) was performed on LKF product after overnight storage. Quality controls on positive fraction consisted in viability and purity of CD133+ cells by cytofluorimetric analysis and clonogenic assays. Microbial tests were performed on the negative fraction. After LKF, patients underwent right portal embolization and infusion of CD133+ cells into the opposite portal vein by a percutaneous access. Evaluation of liver regeneration was performed 30 days after stem cell infusion by spiral CT and galactose clearance. Liver resection was carried out if liver regeneration reached 30-40%. Results: Stem cell mobilization, LKF content and immunoselected cells are detailed in tab 1. No relevant side effects were observed. We obtained an efficient stem cell mobilization in all patients enrolled. No bacterial or fungal contamination was observed in cells infused. Results about liver regeneration and patients' follow up are detailed in table 2. Conclusions: Our approach to liver regeneration was feasible and safe with no relevant side effects. We observed an efficient stem cell mobilization comparable to healthy donors also in liver cancer patients. The infusion of CD133+ cells allowed a significant hepatic tissue regeneration in all patients. Controlled clinical trials are needed to confirm our preliminary results. Disclosures: No relevant conflicts of interest to declare.
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Opara, Chiamaka Belsonia, Nor Kamariah, Jeroen Spooren, Katrin Pollmann, and Sabine Kutschke. "Interesting Halophilic Sulphur-Oxidising Bacteria with Bioleaching Potential: Implications for Pollutant Mobilisation from Mine Waste." Microorganisms 11, no. 1 (January 15, 2023): 222. http://dx.doi.org/10.3390/microorganisms11010222.
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For many years, research on the microbial-dissolution of metals from ores or waste materials mainly focussed on the study of acidophilic organisms. However, most acidophilic bioleaching microorganisms have limited tolerance to high chloride concentrations, thereby requiring fresh water for bioleaching operations. There is a growing interest in the use of seawater for leaching purposes, especially in regions with less access to fresh water. Consequently, there is a need to find halophilic organisms with bioleaching potentials. This study investigated the bioleaching potentials of four moderately halophilic sulphur-oxidising bacteria: Thiomicrospira cyclica, Thiohalobacter thiocyanaticus, Thioclava electrotropha and Thioclava pacifica. Results revealed T. electrotropha and T. pacifica as the most promising for bioleaching. Pure cultures of the two Thioclava strains liberated about 30% Co, and between 8–17% Cu, Pb, Zn, K, Cd, and Mn from a mine waste rock sample from the Neves Corvo mine, Portugal. Microwave roasting of the waste rock at 400 and 500 °C improved the bioleaching efficiency of T. electrotropha for Pb (13.7 to 45.7%), Ag (5.3 to 36%) and In (0 to 27.4%). Mineralogical analysis of the bioleached residues using SEM/MLA-GXMAP showed no major difference in the mineral compositions before or after bioleaching by the Thioclava spp. Generally, the bioleaching rates of the Thioclava spp. are quite low compared to that of the conventional acidophilic bioleaching bacteria. Nevertheless, their ability to liberate potential pollutants (metal(loid)s) into solution from mine waste raises environmental concerns. This is due to their relevance in the biogeochemistry of mine waste dumps, as similar neutrophile halophilic sulphur-oxidising organisms (e.g., Halothiobacillus spp.) have been isolated from mine wastes. On the other hand, the use of competent halophilic microorganisms could be the future of bioleaching due to their high tolerance to Cl- ions and their potential to catalyse mineral dissolution in seawater media, instead of fresh water.
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Dyjach, Dagmara, Petr Walczysko, Nikki Horn, Mark Williams, and Anastasia Sobolewski. "Tu1849 Juxtapositioning of Neutrophils and Macrophages With Colonic Stem Cells, and Mobilisation of Neutrophils to the Surface Epithelium, Following Luminal Microbial Input." Gastroenterology 142, no. 5 (May 2012): S—860. http://dx.doi.org/10.1016/s0016-5085(12)63336-8.
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Rodionov, Andrei, Sara L. Bauke, Christian von Sperber, Carmen Hoeschen, Ellen Kandeler, Jens Kruse, Hans Lewandowski, et al. "Biogeochemical cycling of phosphorus in subsoils of temperate forest ecosystems." Biogeochemistry 150, no. 3 (October 2020): 313–28. http://dx.doi.org/10.1007/s10533-020-00700-8.
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Abstract Tree roots penetrate the soil to several meters depth, but the role of subsoils for the supply of nutrient elements such as phosphorus (P) to the trees is poorly understood. Here, we tested the hypothesis that increased P deficiency in the topsoil results in an increased microbial recycling of P from the forest subsoil. We sampled soils from four German temperate forest sites representing a gradient in total P stocks. We analyzed the oxygen isotopic composition of HCl-extractable phosphate (δ18OP) and identified differences in P speciation with increasing soil depth using X-ray absorption near-edge structure (XANES) spectroscopy. We further determined microbial oxygen demand with and without nutrient supply at different soil depths to analyse nutrient limitation of microbial growth and used nanoscale secondary ion mass spectrometry (NanoSIMS) to visualize spatial P gradients in the rhizosphere. We found that δ18OP values in the topsoil of all sites were close to the isotopic signal imparted by biological cycling when oxygen isotopes in phosphate are exchanged by enzymatic activity. However, with increasing soil depth and increasing HCl-P concentrations, δ18Ο values continuously decreased towards values expected for primary minerals in parent material at depths below 60 cm at sites with high subsoil P stocks and below more than 2 m at sites with low subsoil P stocks, respectively. For these depths, XANES spectra also indicated the presence of apatite. NanoSIMS images showed an enrichment of P in the rhizosphere in the topsoil of a site with high P stocks, while this P enrichment was absent at a site with low P stocks and in both subsoils. Addition of C, N and P alone or in combination revealed that microbial activity in subsoils of sites with low P stocks was mostly P limited, whereas sites with high P stocks indicated N limitation or N and P co-limitation. We conclude that subsoil P resources are recycled by trees and soil microorganisms. With continued weathering of the bedrock and mobilisation of P from the weathered rocks, P cycling will proceed to greater depths, especially at sites characterised by P limitation.
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Zoysa, A. K. N., P. Loganathan, and M. J. Hedley. "Effect of forms of nitrogen supply on mobilisation of phosphorus from a phosphate rock and acidification in the rhizosphere of tea." Soil Research 36, no. 3 (1998): 373. http://dx.doi.org/10.1071/s97079.
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Nitrogen (N) is the main fertiliser input to tea plantations because of the large removal of this element with regular harvests of young shoots in the field. The form of N supply is known to influence the uptake of other plant nutrients, notably phosphorus (P), through its effect on soil pH in the rhizosphere. A glasshouse study was conducted to test the effect of N form (NH +4, NO-3 , or both) on the transformation of soil P in the rhizosphere and its availability to tea (Camellia sinensis L.) plants fertilised with sparingly soluble Eppawala phosphate rock (EPR). Four-month-old tea (TRI 2025) plants were grown in rhizosphere study containers containing an Ultisol from Sri Lanka (pH 4 ·5 in water) amended with EPR and KCl at 200 g P or K/g soil, and mixed with (NH4)2SO4 (100% NH+4 -N), NH4NO3 (50% NH+4 -N and 50% NO-3 -N), and Ca(NO3)2 (100% NO-3 -N) at the rate of 200 g N/g soil, with a control (no N fertiliser), as treatments. Rhizosphere pH decreased compared with the bulk soil when N was supplied as NH+4 or NH+4 +NO-3 forms, and increased when N was supplied as NO-3. The cation{anion balance estimations in the plants showed that the plants had taken up more NO-3 than NH+4 even in (NH4)2SO4 treated soil, suggesting high nitrification rates, especially in the rhizosphere, in spite of using a nitrification inhibitor. More EPR dissolved in the rhizosphere compared with that in the bulk soil, regardless of the N form applied. The (NH4)2SO4 treatment had the highest dissolution rate of EPR in the rhizosphere, whereas Ca(NO3)2 treatment had the lowest, reflecting the degree of acidification in the rhizosphere. Resin-P and NaOH-Pi (inorganic P) concentrations were lower and NaOH-Po (organic P) concentration was higher in the rhizosphere than in the bulk soil. Plant and possible microbial uptake of P is the main reason for the decrease in resin-P and NaOH-Pi. The increase in NaOH-Po concentration in the rhizosphere is believed to be due to transformation of Pi to Po by the high microbial activity in the rhizosphere. The (NH4)2SO4 treatment caused the highest depletion of resin-P but lowest depletion of NaOH-Pi, probably due to the fixation of P by the soils at the low pH in the rhizosphere. The study revealed that the use of the NH+4 form of fertiliser can increase acidification in tea rhizosphere compared with bulk soil and this can enhance the effectiveness of PR fertiliser utilisation by tea plants.
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Husband, S., K. E. Fish, I. Douterelo, and J. Boxall. "Linking discolouration modelling and biofilm behaviour within drinking water distribution systems." Water Supply 16, no. 4 (April 1, 2016): 942–50. http://dx.doi.org/10.2166/ws.2016.045.
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High quality drinking water exits modern treatment works, yet water quality degradation such as discolouration continues to occur within drinking water distribution systems (DWDS). Discolouration is observed globally, suggesting a common process despite variations in source, treatment, disinfection and network configurations. The primary cause of discolouration has been identified as mobilisation of particulate material from pipe walls and the verified Prediction of Discolouration in Distribution Systems (PODDS) model uses measurable network hydraulics to simulate this response. In this paper the cohesive properties of discolouration material are explored and it is hypothesised that in simulating the turbidity response, the PODDS model is actually describing the development and cohesive strength behaviour of biofilms. Applying this concept can therefore facilitate a rapid and simple assessment of DWDS biofilm activity. A review of the findings from PODDS studies conducted internationally is presented, focussing on the macro or observable aspects of discolouration. These are compared and contrasted with associated biofilm studies which consider discolouration material at the micro-scale. Combining the results from these (past) studies to improve the understanding of interactions between microbial ecology and discolouration are discussed with a view to DWDS operational strategies that safeguard and optimise drinking water supply.
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Zhang, Feng, Rongping Wang, Weimin Yu, Jiawei Liang, and Xinrong Liao. "Influences of a vermicompost application on the phosphorus transformation and microbial activity in a paddy soil." Soil and Water Research 15, No. 4 (September 21, 2020): 199–210. http://dx.doi.org/10.17221/91/2019-swr.
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A pot experiment was conducted to investigate the effects of a vermicompost (VC) application on the phosphorus (P) transformation and microbial activity in a paddy soil. Changes in the following P forms were investigated: resin-P, concentrated HCl extracted inorganic (C.HCl-P<sub>i</sub>) and organic P (C.HCl-P<sub>o</sub>), diluted HCl extracted inorganic P (D.HCl-P<sub>i</sub>), NaHCO<sub>3</sub> extracted inorganic (NaHCO<sub>3</sub>-P<sub>i</sub>) and organic P (NaHCO<sub>3</sub>-P<sub>o</sub>), NaOH extracted inorganic (NaOH-P<sub>i</sub>) and organic P (NaOH-P<sub>o</sub>), and residual P. The results showed that the vermicompost application significantly (P < 0.05) affected the pH, redox potential (Eh), water soluble Fe(II), HCl-extractable Fe(II), microbial biomass carbon (MBC), microbial biomass P (MBP), MBC/MBP ratio, and acid phosphatase activity (APA) of the paddy soil. In particular, the HCl-extractable Fe(II) increased by 25–56% with the vermicompost application when compared to the control (CK). With the exception of C.HCl-P<sub>i</sub>, the vermicompost application greatly increased the contents of the various P forms in the soil. In particular, the labile P (resin-P, NaHCO<sub>3</sub>-P<sub>i</sub>, and NaHCO<sub>3</sub>-P<sub>o</sub>) and moderately stable P (NaOH-P<sub>i</sub> and NaOH-P<sub>o</sub>) were significantly (P < 0.01) increased. The correlation analyses showed that NaHCO<sub>3</sub>-P<sub>i</sub> was significantly and positively related to the MBC, MBP, and APA, while NaHCO<sub>3</sub>-P<sub>o</sub> was significantly and negatively related to the MBC, MBP, and APA. Both NaOH-P<sub>i</sub> and C.HCl-P<sub>i</sub> were significantly and negatively related to the APA. Both NaOH-P<sub>o</sub> and C.HCl-P<sub>o</sub> were significantly and positively related to the MBP, while NaOH-P<sub>i</sub> was significantly and negatively related to the MBP. These results indicated that a vermicompost application could effectively enhance the dissolution and reduction of Fe and the consequent mobilisation of NaOH-P<sub>i</sub>. In addition, the vermicompost application significantly (P < 0.01) increased the APA and effectively mobilised the NaOH-P<sub>o</sub>.
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Harvey, P. R., R. A. Warren, and S. Wakelin. "Potential to improve root access to phosphorus: the role of non-symbiotic microbial inoculants in the rhizosphere." Crop and Pasture Science 60, no. 2 (2009): 144. http://dx.doi.org/10.1071/cp08084.
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Phosphate anions in soil solution are extremely reactive and may be rapidly immobilised in the soil through precipitation and adsorption reactions, resulting in sparingly soluble forms of phosphorus (P) that are essentially unavailable to plants. This low P-fertiliser efficiency is often offset through high application rates, which are economically and environmentally unsustainable and not an available option for organic producers. Microorganisms play a fundamental role in the biogeochemical cycling of inorganic and organic P in the rhizosphere and detritusphere. Free-living rhizosphere microbes can directly increase the availability of phosphate to plant roots via mechanisms associated with solubilisation and mineralisation of P from inorganic and organic forms of total soil P. These include releasing organic anions, H+ ions, phosphatases, and cation chelating compounds into the rhizosphere. Many soil-borne microbes also increase P availability indirectly by producing phytohormones that increase root density and function. There is increasing interest worldwide in the use of rhizosphere microorganisms as inoculants to increase P availability for agricultural production. Recent research has focussed on developing actively sporulating Penicillium fungi known to express mechanisms to enhance P mobilisation and therefore, considered to be a key component of the mycoflora involved in P cycling in soils. Penicillium species do not exhibit specific plant or soil associations and have a broad agro-ecological range, indicating their potential to be developed as inoculants for a range of plant production systems. Successful adoption of microbial inoculants requires a thorough understanding of their rhizosphere ecology, genetic stability, and the mechanisms associated with enhancing P availability in soils and plant-growth promotion. This will provide a better understanding of which inoculants to use under particular agro-ecological conditions for increased efficacy and consistent performance.
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Finlay, Roger D., Shahid Mahmood, Nicholas Rosenstock, Emile B. Bolou-Bi, Stephan J. Köhler, Zaenab Fahad, Anna Rosling, et al. "Reviews and syntheses: Biological weathering and its consequences at different spatial levels – from nanoscale to global scale." Biogeosciences 17, no. 6 (March 25, 2020): 1507–33. http://dx.doi.org/10.5194/bg-17-1507-2020.
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Abstract. Plant nutrients can be recycled through microbial decomposition of organic matter but replacement of base cations and phosphorus, lost through harvesting of biomass/biofuels or leaching, requires de novo supply of fresh nutrients released through weathering of soil parent material (minerals and rocks). Weathering involves physical and chemical processes that are modified by biological activity of plants, microorganisms and animals. This article reviews recent progress made in understanding biological processes contributing to weathering. A perspective of increasing spatial scale is adopted, examining the consequences of biological activity for weathering from nanoscale interactions, through in vitro and in planta microcosm and mesocosm studies, to field experiments, and finally ecosystem and global level effects. The topics discussed include the physical alteration of minerals and mineral surfaces; the composition, amounts, chemical properties, and effects of plant and microbial secretions; and the role of carbon flow (including stabilisation and sequestration of C in organic and inorganic forms). Although the predominant focus is on the effects of fungi in forest ecosystems, the properties of biofilms, including bacterial interactions, are also discussed. The implications of these biological processes for modelling are discussed, and we attempt to identify some key questions and knowledge gaps, as well as experimental approaches and areas of research in which future studies are likely to yield useful results. A particular focus of this article is to improve the representation of the ways in which biological processes complement physical and chemical processes that mobilise mineral elements, making them available for plant uptake. This is necessary to produce better estimates of weathering that are required for sustainable management of forests in a post-fossil-fuel economy. While there are abundant examples of nanometre- and micrometre-scale physical interactions between microorganisms and different minerals, opinion appears to be divided with respect to the quantitative significance of these observations for overall weathering. Numerous in vitro experiments and microcosm studies involving plants and their associated microorganisms suggest that the allocation of plant-derived carbon, mineral dissolution and plant nutrient status are tightly coupled, but there is still disagreement about the extent to which these processes contribute to field-scale observations. Apart from providing dynamically responsive pathways for the allocation of plant-derived carbon to power dissolution of minerals, mycorrhizal mycelia provide conduits for the long-distance transportation of weathering products back to plants that are also quantitatively significant sinks for released nutrients. These mycelial pathways bridge heterogeneous substrates, reducing the influence of local variation in C:N ratios. The production of polysaccharide matrices by biofilms of interacting bacteria and/or fungi at interfaces with mineral surfaces and roots influences patterns of production of antibiotics and quorum sensing molecules, with concomitant effects on microbial community structure, and the qualitative and quantitative composition of mineral-solubilising compounds and weathering products. Patterns of carbon allocation and nutrient mobilisation from both organic and inorganic substrates have been studied at larger spatial and temporal scales, including both ecosystem and global levels, and there is a generally wider degree of acceptance of the “systemic” effects of microorganisms on patterns of nutrient mobilisation. Theories about the evolutionary development of weathering processes have been advanced but there is still a lack of information connecting processes at different spatial scales. Detailed studies of the liquid chemistry of local weathering sites at the micrometre scale, together with upscaling to soil-scale dissolution rates, are advocated, as well as new approaches involving stable isotopes.
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Stott, Rebecca, Robert Davies-Colley, John Nagels, Andrea Donnison, Colleen Ross, and Richard Muirhead. "Differential behaviour of Escherichia coli and Campylobacter spp. in a stream draining dairy pasture." Journal of Water and Health 9, no. 1 (February 3, 2011): 59–69. http://dx.doi.org/10.2166/wh.2010.061.
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The faecal indicator bacterium Escherichia coli and thermotolerant Campylobacter spp., which are potentially pathogenic, were investigated in the Toenepi Stream draining a pastoral catchment dominated by dairying. Bacteria concentrations were monitored routinely at fortnightly intervals over 12 months and intensively during storm events to compare the transport dynamics of bacterial indicator and pathogen under varying hydro-meteorological conditions. Routine monitoring indicated median concentrations of 345 E. coli MPN 100 ml−1 and relatively low concentrations of 2.3 Campylobacter MPN 100 ml−1. The bacterial flux was three orders of magnitude greater under elevated stream flow compared with base-flow. E. coli peak concentrations occurred very close to the turbidity peak and consistently ahead of the Campylobacter spp. peak (which was close to the hydrograph peak). We postulate that, under flood conditions, the E. coli peak reflects the entrainment and mobilisation of in-stream stores on the flood wave front. In contrast, Campylobacter spp. are derived from wash-in from land stores upstream and have travelled at the mean water velocity which is slower than the speed of the flood wave. Our findings of different dynamics for E. coli and Campylobacter spp. suggest that mitigation to reduce faecal microbial impacts from farms will need to take account of these differences.
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Gahan, Jacinta, Orla O’Sullivan, Paul D. Cotter, and Achim Schmalenberger. "Arbuscular Mycorrhiza Support Plant Sulfur Supply through Organosulfur Mobilizing Bacteria in the Hypho- and Rhizosphere." Plants 11, no. 22 (November 11, 2022): 3050. http://dx.doi.org/10.3390/plants11223050.
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This study aimed to elucidate the role of bacteria colonising mycorrhizal hyphae in organically bound sulfur mobilisation, the dominant soil sulfur source that is not directly plant available. The effect of an intact mycorrhizal symbiosis with access to stable isotope organo-34S enriched soils encased in 35 µm mesh cores was tested in microcosms with Agrostis stolonifera and Plantago lanceolata. Hyphae and associated soil were sampled from static mesh cores with mycorrhizal ingrowth and rotating mesh cores that exclude mycorrhizal ingrowth as well as corresponding rhizosphere soil, while plant shoots were analysed for 34S uptake. Static cores increased uptake of 34S at early stages of plant growth when sulfur demand appeared to be high and harboured significantly larger populations of sulfonate mobilising bacteria. Bacterial and fungal communities were significantly different in the hyphospheres of static cores when compared to rotating cores, not associated with plant hosts. Shifts in bacterial and fungal communities occurred not only in rotated cores but also in the rhizosphere. Arylsulfatase activity was significantly higher in the rhizosphere when cores stayed static, while atsA and asfA gene diversity was distinct in the microcosms with static and rotating cores. This study demonstrated that AM symbioses can promote organo-S mobilization and plant uptake through interactions with hyphospheric bacteria, enabling AM fungal ingrowth into static cores creating a positive feedback-loop, detectable in the microbial rhizosphere communities.
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Bolan, N. S., and V. P. Duraisamy. "Role of inorganic and organic soil amendments on immobilisation and phytoavailability of heavy metals: a review involving specific case studies." Soil Research 41, no. 3 (2003): 533. http://dx.doi.org/10.1071/sr02122.
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Soil is not only considered as a 'source' of nutrients for plant growth, but also as a 'sink' for the removal of contaminants from industrial and agricultural waste materials. The origin of heavy metal contamination of soils may be anthropogenic as well as geogenic. With greater public awareness of the implications of contaminated soils on human and animal health, there has been increasing interest amongst the scientific community in developing cost-effective and community-acceptable remediation technologies for contaminated sites. Unlike organic contaminants, most metals do not undergo microbial or chemical degradation, thereby resulting in their accumulation in soils. The mobilisation of metals in soils for plant uptake and leaching to groundwater can, however, be minimised through chemical and biological immobilisation. Recently there has been increasing interest in the immobilisation of metals using a range of inorganic compounds, such as lime and phosphate (P) compounds, and organic compounds, such as 'exceptional quality' biosolids. In this review paper, the results from selected New Zealand studies on the potential value of a range of soil amendments (phosphate compounds, liming materials, and biosolids) in the immobilisation of cadmium (Cd), chromium (Cr), and copper (Cu) is discussed in relation to remediation of contaminated soils. These case studies have indicated that lime is effective in reducing the phytoavailability of Cd and Cr(III), phosphate compounds are effective for Cd, and organic amendments are effective for Cu and Cr(VI). The mechanisms proposed for the immobilisation and consequent reduction in the phytoavailability of metals by the soil amendments include: enhanced metal adsorption through increased surface charge (e.g. phosphate-induced metal adsorption), increased formation of organic and inorganic metal complexes (e.g. cadmium-phosphate complex and copper-organic matter complex), precipitation of metals (e.g. chromic hydroxide), and reduction of metals from higher valency mobile form to lower valency immobile form [e.g. Cr(VI) to Cr(III)]. These case studies indicated that since bioavailability is the key factor for remediation technologies, chemical or biological immobilisation of metals may be a preferred option.
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Dybowska, Agnieszka, Paul Schofield, Laura Newsome, Richard Herrington, Julian Mosselmans, Burkhard Kaulich, Majid Kazemian, et al. "Evolution of the Piauí Laterite, Brazil: Mineralogical, Geochemical and Geomicrobiological Mechanisms for Cobalt and Nickel Enrichment." Minerals 12, no. 10 (October 14, 2022): 1298. http://dx.doi.org/10.3390/min12101298.
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The Piauí laterite (NE Brazil) was initially evaluated for Ni but also contains economic concentrations of Co. Our investigations aimed to characterise the Co enrichment within the deposit; by understanding the mineralogy we can better design mineral processing to target Co recovery. The laterite is heterogeneous on the mineralogical and lithological scale differing from the classic schematic profiles of nickel laterites, and while there is a clear transition from saprolite to more ferruginous units, the deposit also contains lateral and vertical variations that are associated with both the original intrusive complex and also the nature of fluid flow, redox cycling and fluctuating groundwater tables. The deposit is well described by the following six mineralogical and geochemical units: SAPFE, a clay bearing ferruginous saprolite; SAPSILFE, a silica dominated ferruginous saprolite; SAPMG, a green magnesium rich chlorite dominated saprolite; SAPAL, a white-green high aluminium, low magnesium saprolite; saprock, a serpentine and chlorite dominated saprolite and the serpentinite protolith. Not all of these units are ‘ore bearing’. Ni is concentrated in a range of nickeliferous phyllosilicates (0.1–25 wt%) including serpentines, talc and pimelite, goethite (up to 9 wt%), magnetite (2.8–14 wt%) and Mn oxy-hydroxides (0.35–19 wt%). Lower levels of Ni are present in ilmenites, chromites, chlorite and distinct small horizons of nickeliferous silica (up to 3 wt% Ni). With respect to Co, the only significant chemical correlation is with Mn, and Mn oxy-hydroxides contain up to 14 wt% Co. Cobalt is only present in goethite when Mn is also present, and these goethite grains contain an average of 0.19 wt% Co (up to a maximum of 0.65 wt%). The other main Co bearing minerals are magnetite (0.41–1.89 wt%), chlorite (up to 0.45 wt%) and ilmenite (up to 0.35 wt%). Chemically there are three types of Mn oxy-hydroxide, asbolane, asbolane-lithiophorite intermediates and romanechite. Spatially resolved X-ray absorption spectroscopy analysis suggests that the Co is present primarily as octahedrally bound Co3+ substituted directly into the MnO6 layers of the asbolane-lithiophorite intermediates. However significant levels of Co2+ are evident within the asbolane-lithiophorite intermediates, structurally bound along with Ni in the interlayer between successive MnO6 layers. The laterite microbial community contains prokaryotes and few fungi, with the highest abundance and diversity closest to ground level. Microorganisms capable of metal redox cycling were identified to be present, but microcosm experiments of different horizons within the deposit demonstrated that stimulated biogeochemical cycling did not contribute to Co mobilisation. Correlations between Co and Mn are likely to be a relic of parent rock weathering rather than due to biogeochemical processes; a conclusion that agrees well with the mineralogical associations.
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Severmann, S. "Microbially Mediated Mobilisation of Redox-Sensitive Metals in Relict Hydrothermal Sulphide Deposits." Mineralogical Magazine 62A, no. 3 (1998): 1367–68. http://dx.doi.org/10.1180/minmag.1998.62a.3.50.
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Calero Preciado, Carolina, Joby Boxall, Víctor Soria-Carrasco, Soledad Martínez, and Isabel Douterelo. "Implications of Climate Change: How Does Increased Water Temperature Influence Biofilm and Water Quality of Chlorinated Drinking Water Distribution Systems?" Frontiers in Microbiology 12 (June 8, 2021). http://dx.doi.org/10.3389/fmicb.2021.658927.
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Temperature variation can promote physico-chemical and microbial changes in the water transported through distribution systems and influence the dynamics of biofilms attached to pipes, thus contributing to the release of pathogens into the bulk drinking water. An experimental real-scale chlorinated DWDS was used to study the effect of increasing temperature from 16 to 24°C on specific pathogens, bacterial-fungal communities (biofilm and water samples) and determine the risk of material accumulation and mobilisation from the pipes into the bulk water. Biofilm was developed for 30 days at both temperatures in the pipe walls, and after this growth phase, a flushing was performed applying 4 gradual steps by increasing the shear stress. The fungal-bacterial community characterised by Illumina MiSeq sequencing, and specific pathogens were studied using qPCR: Mycobacterium spp., Mycobacterium avium complex, Acanthamoeba spp., Pseudomonas aeruginosa, Legionella pneumophilia, and Stenotrophomonas maltophilia. Sequencing data showed that temperature variation significantly modified the structure of biofilm microbial communities from the early stages of biofilm development. Regarding bacteria, Pseudomonas increased its relative abundance in biofilms developed at 24°C, while fungal communities showed loss of diversity and richness, and the increase in dominance of Fusarium genus. After the mobilisation phase, Pseudomonas continued being the most abundant genus at 24°C, followed by Sphingobium and Sphingomonas. For biofilm fungal communities after the mobilisation phase, Helotiales incertae sedis and Fusarium were the most abundant taxa. Results from qPCR showed a higher relative abundance of Mycobacterium spp. on day 30 and M. avium complex throughout the growth phase within the biofilms at higher temperatures. The temperature impacts were not only microbial, with physical mobilisation showing higher discolouration response and metals release due to the increased temperature. While material accumulation was accelerated by temperature, it was not preferentially to either stronger or weaker biofilm layers, as turbidity results during the flushing steps showed. This research yields new understanding on microbial challenges that chlorinated DWDS will undergo as global temperature rises, this information is needed in order to protect drinking water quality and safety while travelling through distribution systems.
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Bassil, Naji M., Joe S. Small, and Jonathan R. Lloyd. "Enhanced microbial degradation of irradiated cellulose under hyperalkaline conditions." FEMS Microbiology Ecology 96, no. 7 (May 27, 2020). http://dx.doi.org/10.1093/femsec/fiaa102.
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ABSTRACT Intermediate-level radioactive waste includes cellulosic materials, which under the hyperalkaline conditions expected in a cementitious geological disposal facility (GDF) will undergo abiotic hydrolysis forming a variety of soluble organic species. Isosaccharinic acid (ISA) is a notable hydrolysis product, being a strong metal complexant that may enhance the transport of radionuclides to the biosphere. This study showed that irradiation with 1 MGy of γ-radiation under hyperalkaline conditions enhanced the rate of ISA production from the alkali hydrolysis of cellulose, indicating that radionuclide mobilisation to the biosphere may occur faster than previously anticipated. However, irradiation also made the cellulose fibres more available for microbial degradation and fermentation of the degradation products, producing acidity that inhibited ISA production via alkali hydrolysis. The production of hydrogen gas as a fermentation product was noted, and this was associated with a substantial increase in the relative abundance of hydrogen-oxidising bacteria. Taken together, these results expand our conceptual understanding of the mechanisms involved in ISA production, accumulation and biodegradation in a biogeochemically active cementitious GDF.
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Clarke, AM, R. Kirby, and PD Rose. "Molecular microbial ecology of lignocellulose mobilisation as a carbon source in mine drainage wastewater treatment." Water SA 30, no. 5 (December 4, 2007). http://dx.doi.org/10.4314/wsa.v30i5.5179.
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Gaylarde, Christine C., and Jose Antonio Baptista-Neto. "Microbiologically induced aesthetic and structural changes to dimension stone." npj Materials Degradation 5, no. 1 (June 17, 2021). http://dx.doi.org/10.1038/s41529-021-00180-7.
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AbstractDimension stone is natural rock prepared for building use. It is rapidly colonised by microorganisms that cause discoloration (mainly cyanobacteria, algae and fungi) and structural damage. Microbial mobilisation of ions leads to new superficial or internal deposits, weakening the structure. Cyanobacteria and fungi may penetrate, filling pores or creating new spaces. Lichens, fungus/phototroph associations, colonise surfaces and damage stone through ingrowing rhizines and acid production. Initial degradation produces conditions suitable for germination of seeds of higher plants and further destruction. Emerging techniques to elucidate stone-cell interactions and control of initial biofilm formation that eventuates in stone disintegration are discussed.
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Kantar, Cetin, Aydeniz Demir, and Nurcan Koleli. "Effect of exopolymeric substances on the kinetics of sorption and desorption of trivalent chromium in soil." Chemical Papers 68, no. 1 (January 1, 2014). http://dx.doi.org/10.2478/s11696-013-0427-4.
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AbstractLaboratory batch sorption-desorption and column experiments were performed to better understand the effects of microbial exopolymeric substances (EPS) on Cr(III) sorption/desorption rates in the soil-water system. The experiments were carried out in two different modes: one mode (sorption) in which Cr(III) and EPS were applied simultaneously, and the other (desorption) included the sequential application of Cr(III) and EPS to the soil-water system. The batch sorption and desorption experiments showed that, while chromium(III) desorption was significantly enhanced in the presence of EPS relative to non-EPS-containing systems, the desorption rates were much smaller than the sorption rates, and the fraction dissolved by EPS accounted for only a small portion of the total chromium initially sorbed onto soil minerals. Similarly, the column experiments suggested that, while the microbial EPS led to an increase in Cr dissolution relative to non-EPS-containing systems, only a small portion of the total chromium initially added to the soil was mobilised. The differences observed in Cr sorption and desorption rates can be explained through the very low solubility and strong interactions of chromium species with soil minerals as well as the mass transfer effects associated with low diffusion rates. The overall results suggest that, while microbial EPS may play an important role in microbial Cr(VI) treatment in sub-surface systems due to the formation of soluble Cr-EPS complexes, the extent and degree of Cr mobilisation are highly dependent on the type of initial Cr sorption.
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Nel, Jan G., Annette J. Theron, Roger Pool, Chrisna Durandt, Gregory R. Tintinger, and Ronald Anderson. "Neutrophil extracellular traps and their role in health and disease." South African Journal of Science Volume 112, Number 1/2 (February 1, 2016). http://dx.doi.org/10.17159/sajs.2016/20150072.
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Abstract The human innate immune system is indispensable for protection against potentially invasive microbial and viral pathogens, either neutralising them or containing their spread until effective mobilisation of the slower, adaptive (specific), immune response. Until fairly recently, it was believed that the human innate immune system possessed minimal discriminatory activity in the setting of a rather limited range of microbicidal or virucidal mechanisms. However, recent discoveries have revealed that the innate immune system possesses an array of novel pathogen recognition mechanisms, as well as a resourceful and effective alternative mechanism of phagocyte (predominantly neutrophil)-mediated, anti-infective activity known as NETosis. The process of NETosis involves an unusual type of programmed, purposeful cell death, resulting in the extracellular release of a web of chromatin heavily impregnated with antimicrobial proteins. These structures, known as neutrophil extracellular traps (NETs), immobilise and contribute to the eradication of microbial pathogens, ensuring that the anti-infective potential of neutrophils is sustained beyond the lifespan of these cells. The current review is focused on the mechanisms of NETosis and the role of this process in host defence. Other topics reviewed include the potential threats to human health posed by poorly controlled, excessive formation of NETs, specifically in relation to development of autoimmune and cardiovascular diseases, as well as exacerbation of acute and chronic inflammatory disorders of the airways.
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HAN, ZHENGDONG, Alan Levett, Mansour EDRAKI, Michael W. M. Jones, Daryl L. Howard, and Gordon Southam. "Microbially Influenced Tungsten Mobilisation and Formation of Secondary Minerals in Wolframite Tailings." SSRN Electronic Journal, 2022. http://dx.doi.org/10.2139/ssrn.4226460.
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Han, Zhengdong, Alan Levett, Mansour Edraki, Michael W. M. Jones, Daryl Howard, and Gordon Southam. "Microbially influenced tungsten mobilisation and formation of secondary minerals in wolframite tailings." Journal of Hazardous Materials, November 2022, 130508. http://dx.doi.org/10.1016/j.jhazmat.2022.130508.
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McGrory, Ellen, Tiernan Henry, Peter Conroy, and Liam Morrison. "Occurrence, Geochemistry and Speciation of Elevated Arsenic Concentrations in a Fractured Bedrock Aquifer System." Archives of Environmental Contamination and Toxicology, September 14, 2021. http://dx.doi.org/10.1007/s00244-021-00887-3.
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AbstractThe presence of elevated arsenic concentrations (≥ 10 µg L−1) in groundwaters has been widely reported in areas of South-East Asia with recent studies showing its detection in fractured bedrock aquifers is occurring mainly in regions of north-eastern USA. However, data within Europe remain limited; therefore, the objective of this work was to understand the geochemical mobilisation mechanism of arsenic in this geologic setting using a study site in Ireland as a case study. Physicochemical (pH, Eh, d-O2), trace metals, major ion and arsenic speciation samples were collected and analysed using a variety of field and laboratory-based techniques and evaluated using statistical analysis. Groundwaters containing elevated dissolved arsenic concentrations (up to 73.95 µg L−1) were characterised as oxic-alkali groundwaters with the co-occurrence of other oxyanions (including Mo, Se, Sb and U), low dissolved concentrations of Fe and Mn, and low Na/Ca ratios indicated that arsenic was mobilised through alkali desorption of Fe oxyhydroxides. Arsenic speciation using a solid-phase extraction methodology (n = 20) showed that the dominant species of arsenic was arsenate, with pH being a major controlling factor. The expected source of arsenic is sulphide minerals within fractures of the bedrock aquifer with transportation of arsenic and other oxyanion forming elements facilitated by secondary Fe mineral phases. However, the presence of methylarsenical compounds detected in groundwaters illustrates that microbially mediated mobilisation processes may also be (co)-occurring. This study gives insight into the geochemistry of arsenic mobilisation that can be used to further guide research needs in this area for the protection of groundwater resources.