A subcellular level study of copper speciation reveals the synergistic mechanism of microbial cells and EPS involved in copper binding in bacterial biofilms.

The synergistic cooperation of microbial cells and their extracellular polymeric substances (EPS) in biofilms is critical for the biofilm's resistance to heavy metals and the migration and transformation of heavy metals. However, the effects of different components of biofilms have not been fully understood. In this study, the spatial distribution and speciation of copper in the colloidal EPS, capsular EPS, cell walls and membranes, and intracellular fraction of unsaturated Pseudomonas putida (P.

Interaction between copper and extracellular nucleic acids in the EPS of unsaturated Pseudomonas putida CZ1 biofilm.

The role of extracellular DNA (eDNA) in biofilm in heavy metal complexation has been little reported. In this study, the interaction between the extracellular fraction of unsaturated biofilms and Cu was studied using random amplified polymorphic DNA (RAPD) and synchrotron-based X-ray absorption spectroscopy (XAS) analyses. Under Cu stress, the amount of eDNA was about 10-fold higher than the treatment without Cu stress, which was substantially more than the amount of intracellular DNA (iDNA) present in the biofilm.

Spatial Pattern of Copper Phosphate Precipitation Involves in Copper Accumulation and Resistance of Unsaturated CZ1 Biofilm.

Bacterial biofilms are spatially structured communities that contain bacterial cells with a wide range of physiological states. The spatial distribution and speciation of copper in unsaturated CZ1 biofilms that accumulated 147.0 mg copper per g dry weight were determined by transmission electron microscopy coupled with energy dispersive X-ray analysis, and micro-X-ray fluorescence microscopy coupled with micro-X-ray absorption near edge structure (micro-XANES) analysis.

Effect of heavy-metal-resistant bacteria on enhanced metal uptake and translocation of the Cu-tolerant plant, Elsholtzia splendens.

A hydroponics trial was employed to study the effects of Pseudomonas putida CZ1 (CZ1), a heavy-metal-resistant bacterial strain isolated from the rhizosphere of Elsholtzia splendens (E. splendens), on the uptake and translocation of copper (Cu) in E. splendens.

Responses of unsaturated Pseudomonas putida CZ1 biofilms to environmental stresses in relation to the EPS composition and surface morphology.

The extracellular polymeric substance (EPS) and surface properties of unsaturated biofilms of a heavy metal-resistant rhizobacterium Pseudomonas putida CZ1, in response to aging, pH, temperature and osmotic stress, were studied by quantitative analysis of EPS and atomic force microscope. It was found that EPS production increased approximately linearly with culture time, cells in the air-biofilm interface enhanced EPS production and decreased cell volume to cope with nutrient depletion during aging. Low pH, high temperature and certain osmotic stress (120 mM NaCl) distinctly stimulated EPS production, and the main component enhanced was extracellular protein.

Assessment of phenanthrene bioavailability in aged and unaged soils by mild extraction.

It has become apparent that the threat of an organic pollutant in soil is directly related to its bioavailable fraction and that the use of total contaminant concentrations as a measure of potential contaminant exposure to plants or soil organisms is inappropriate. In light of this, non-exhaustive extraction techniques are being investigated to assess their appropriateness in determining bioavailability. To find a suitable and rapid extraction method to predict phenanthrene bioavailability, multiple extraction techniques (i.

Adsorption of copper and zinc by biochars produced from pyrolysis of hardwood and corn straw in aqueous solution.

Biochars produced by pyrolysis of hardwood at 450 °C (HW450) and corn straw at 600 °C (CS600) were characterized and investigated as adsorbents for the removal of Cu(II) and Zn(II) from aqueous solution. The adsorption data were well described by a Langmuir isotherm, with maximum Cu(II) and Zn(II) adsorption capacities of 12.52 and 11.

Sorption and distribution of copper in unsaturated Pseudomonas putida CZ1 biofilms as determined by X-ray fluorescence microscopy.

The spatial and temporal distribution of metals in unsaturated Pseudomonas putida CZ1 biofilms was determined using synchrotron-based X-ray fluorescence microscopy (XRF). It was found that Fe, Mn, and Ca were mainly distributed near the air-biofilm interface of a biofilm grown on 40 mM citrate, while there were two Fe-, Mn-, and Ca-rich layers within a biofilm grown on 10 mM citrate. The sorption of copper by biofilm grown in medium containing 10 mM citrate was rapid, with copper being found throughout the biofilm after only 1 h of exposure.

Enhancement of copper availability and microbial community changes in rice rhizospheres affected by sulfur.

The role of sulfur on the availability of Cu and the bacterial community in rice rhizospheres was investigated by pot experiments. With sulfur addition, pH in rhizosphere soil decreased and Mg(NO₃)₂ extractable Cu increased significantly. The bacterial community composition also changed with sulfur addition.

[Persisters and their effects on microbial biofilm tolerance: a review].

Persisters are a group of special subpopulation of bacteria, only occupying < 0.1% of the whole population but having the characteristics different from the ordinary bacteria and resistant mutants. They have complex formation mechanism, and are difficult to isolate and culture.

Subcellular distribution and chemical forms of cadmium in Phytolacca americana L.

Phytolacca americana L. (pokeweed) is a promising species for Cd phytoextraction with large biomass and fast growth rate. To further understand the mechanisms involved in Cd tolerance and detoxification, the present study investigated subcellular distribution and chemical forms of Cd in pokeweed.

Curli produced by Escherichia coli PHL628 provide protection from Hg(II).

The role of curli, amyloid extracellular fibers, in the tolerance of Escherichia coli PHL628 to Hg(II) was examined. Our findings indicate that by sorbing Hg(II) extracellularly, curli protect the cells. To our knowledge, this is the first time a protective role of curli against toxic metals has been demonstrated.

Lead contamination in different varieties of tea plant (Camellia sinensis L.) and factors affecting lead bioavailability.

Background: There has been increasing concern in recent years about the concentration of lead (Pb) in tea. However, little research has been done to address questions concerning the distribution of Pb in different varieties of tea plant and the differences among tea plant varieties in their uptake and accumulation of Pb from the soil. Therefore the aim of this study was to investigate the accumulation of Pb in different tea plant varieties and the factors affecting Pb bioavailability.

Morphological alterations of Vero cell exposed to coplanar PCB 126 and noncoplanar PCB 153.

Polychlorinated biphenyls (PCBs) are widespread, persistent environmental contaminants that display a complex spectrum of toxicological properties. Exposure to PCBs has been associated with morphological anomalies in cell cultures. However, most mechanistic studies of PCBs' toxic activity have been focused on coplanar congeners.

Copper uptake and its effect on metal distribution in root growth zones of Commelina communis revealed by SRXRF.

To explore the copper uptake mechanisms by the Cu-tolerant plant Commelina communis, the contents of Cu and other metals (including Fe, Zn, and Mn) in roots were detected using atomic absorption spectrometer under transporter inhibitors, partial element deficiency, or Cu excess treatments, while distribution characters of Cu and other metals in root growth zones were investigated by synchrotron radiation X-ray fluorescence spectroscopy (SRXRF). Cu uptake was inhibited by the uncoupler DNP and P-type ATPase inhibitor Na(3)VO(4), not by the Ca(2+) ion channel inhibitor LaCl(3), suggesting that Cu could probably be assimilated actively by root and be related with P-type ATPase, but not through Ca(2+) ion channel. Fe or Zn deficiency could enhance Cu uptake, while 100 μM Cu inhibited Fe, Zn, and Mn accumulation in roots significantly.

Assessment of pyrene bioavailability in soil by mild hydroxypropyl-β-cyclodextrin extraction.

Bioavailability of organic pollutants in soil is currently a much-debated issue in risk assessment of contaminated sites. Ecorisk of an organic pollutant in soil is strongly influenced by the properties of the soil and its contamination history. To evaluate the effect of aging on the availability of pyrene, earthworm (Eisenia fetida) accumulation and chemical extraction by exhaustive and nonexhaustive techniques in soil spiked with a range of pyrene levels (1.

Enhanced phytoremediation potential of polychlorinated biphenyl contaminated soil from e-waste recycling area in the presence of randomly methylated-beta-cyclodextrins.

The crude recycling of electronic and electric waste (e-waste) is now creating soil pollution problems with organic compounds such as polychlorinated biphenyls (PCBs). The present study aimed to compare the phytoremediation potential of four plant species (rice, alfalfa, ryegrass and tall fescue) for PCBs contaminated soil from Taizhou city, one of the largest e-waste recycling centers in China. In addition, the enhanced effects of randomly methylated-beta-cyclodextrins (RAMEB) on PCBs phytoremediation potential were evaluated.

Hormesis response of marine and freshwater luminescent bacteria to metal exposure.

The stimulatory effect of low concentrations of toxic chemicals on organismal metabolism, referred to as hormesis, has been found to be common in the widely used luminescence bioassay. This paper aims to study the hormesis phenomenon in both marine and freshwater luminescent bacteria, named Photobacterium phosphorem and Vibrio qinghaiensis. The effects of Cu (II), Zn (II), Cd (II) and Cr (VI) on luminescence of these two bacteria were studied for 0 to 75 minutes exposure by establishing dose- and time-response curves.

Enhancement of phenanthrene and pyrene degradation in rhizosphere of tall fescue (Festuca arundinacea).

A greenhouse experiment was conducted with varying concentrations of phenanthrene (11-344 mg kg(-1)) and pyrene (15-335 mg kg(-1)) spiked in the soil to evaluate the phytoremediation of PAHs contaminated soil using tall fescue (Festuca arundinacea). After 65-day of tall fescue growth, plant biomass, microbial viable counts, dehydrogenase activity, water-soluble phenolic compounds, phenanthrene and pyrene residual concentrations and removal percentages were determined. The results showed that target PAHs (phenanthrene and pyrene) did not affect plant biomass at lower concentrations but a reduced biomass (only 53.

Interaction of Pseudomonas putida CZ1 with clays and ability of the composite to immobilize copper and zinc from solution.

The present study was conducted to determine the abilities of the living and nonliving Pseudomonas putida CZ1 cells, clays (goethite, kaolinite, smectite and manganite) and their composites to accumulate copper and zinc from a liquid medium, and elucidate the role of microbes on the mobility of heavy metals. Various mixtures of bacteria and clays were exposed to solutions of 0.025 mM or 0.

Effect of sulphur on soil Cu/Zn availability and microbial community composition.

Successful phytoremediation depends mainly on the bioavailability of copper (Cu) and zinc (Zn) in the soil. We studied the potential effects of sulphur (S) amendment on mobility of copper, zinc and microbial community composition in soil under laboratory conditions. The results showed that with S application at 20 g S kg(-1), soil pH decreased about 3 units and the solubility of the Cu and Zn significantly increased after 64 days of incubation.

Identification of ah receptor agonists in soil of E-waste recycling sites from Taizhou area in China.

In recent years, increasing concern has surrounded the consequences of improper electric and electronic waste (e-waste) disposal. In order to mitigate or remediate the potentially severe toxic effects of e-waste recycling on the environment, organisms, and humans, many contaminated sites must first be well-characterized. In this study, soil samples were taken from Taizhou city, one of the largest e-waste disposal centers in China, which was involved in recycling for nearly 30 years.

Particle-facilitated lead and arsenic transport in abandoned mine sites soil influenced by simulated acid rain.

The role of acid rain in affecting Pb and As transport from mine tailings was investigated by pumping simulated acid rain at a infiltration rate of 10.2 cm/h through soil columns. Simulated acid rain with pH of 3.

Heavy metal availability and impact on activity of soil microorganisms along a Cu/Zn contamination gradient.

All the regulations that define a maximum concentration of metals in the receiving soil are based on total soil metal concentration. However, the potential toxicity of a heavy metal in the soil depends on its speciation and availability. We studied the effects of heavy metal speciation and availability on soil microorganism activities along a Cu/Zn contamination gradient.