We report the 4.76-Mb draft genome of Pantoea ananatis GB1, a Gram-negative bacterium of the fami... more We report the 4.76-Mb draft genome of Pantoea ananatis GB1, a Gram-negative bacterium of the family Enterobacteriaceae, isolated from the roots of poplars planted for phytoremediation of a diesel-contaminated plume at the Ford Motor Company site in Genk, Belgium. Strain GB1 promotes plant growth in various hosts and metabolizes hydrocarbons.
Volatile fuel compounds such as fuel oxygenates (FO) (MTBE and ETBE) and BTEX (benzene, toluene, ... more Volatile fuel compounds such as fuel oxygenates (FO) (MTBE and ETBE) and BTEX (benzene, toluene, ethylbenzene and xylene) are some of the most soluble components of fuel. Characterizing the leaching potential of these compounds is essential for predicting their mobility through the soil profile and assessing the risk of groundwater contamination. Plant root exudates can play an important role in the modification of contaminant mobility in soil-plant systems, and such effects should also be considered in leaching studies. Artificially spiked samples of A and B horizons from an alumi-umbric Cambisol were leached in packed-columns and batch experiments using Milli-Q water and plant root exudates as leaching agents. The leaching potential and rate were strongly influenced by soil-contaminant interactions and by the presence of root exudates. Organic matter in A horizon preferably sorbed the most non-polar contaminants, lowering their leaching potential, and this effect was enhanced by the presence of root exudates. On the other hand, the inorganic components of the B horizon, showed a greater affinity for polar molecules, and the presence of root exudates enhanced the desorption of the contaminants. Column experiments resulted in a more realistic protocol than batch tests for predicting the leaching potential of volatile organic compounds in dissimilar soils.
Factors associated with soil acidity are considered to be limiting for plants in many parts of th... more Factors associated with soil acidity are considered to be limiting for plants in many parts of the world. This work was undertaken to investigate the role of the toxicity of hydrogen (H(+)) which seems to have been underconsidered by ecologists as an explanation of the reduced plant growth observed in very acid soils. Racial differences are reported in plant growth response to increasing acidity in the grass Holcus lanatus L. (Yorkshire-fog) and the tree Betula pendula Roth (Silver Birch). Soils and seeds were collected from four Scottish sites which covered a range of soils from acid (organic and mineral) to more base-rich. The sites and their pH (1:2.5 fresh soil:0.01 M CaCl(2)) were: Flanders Moss (FM), pH 3.2+/-0.03; Kippenrait Glen (KP), pH 4.8+/- 0.05; Kinloch Rannoch (KR), pH 6.1+/-0.16; and Sheriffmuir (SMM), pH 4.3+/-0.11. The growth rates of two races of H. lanatus, FM and KP, and three races of B. pendula (SMM, KP and KR) were measured in nutrient solution cultures at pH 2.0 (H. lanatus only), 3.0, 4.0, 5.0, and 5.6. Results showed races from acid organic soils (FM) were H(+)-tolerant while those from acid mineral soils (SMM) were Al(3+)-tolerant but not necessarily H(+)-tolerant. These results confirmed that populations were separately adapted to H(+) or Al(3+) toxicity and this was dependent upon the soil characteristics at their site of collection. The fact of plant adaptation to H(+) toxicity supports the view that this is an important factor in very acid soils.
Se evalúa la eficiencia de Serpyllifolium ssp. Lusitanicum (Brassicaceae), un hiperacumulador de ... more Se evalúa la eficiencia de Serpyllifolium ssp. Lusitanicum (Brassicaceae), un hiperacumulador de Ni que crece en los suelos serpentiníticos de la región de Tras Os Montes (NE Portugal), para su uso en fitoextracción de metales en suelos de mina. Para ello se hizo un ensayo de invernadero con Alyssum serpyllifolium y dos suelos de mina (SM1 y SM2). Se estudió la capacidad de esta especie para acceder a diferentes fracciones metálicas del suelo, así como los cambios que inducía sobre la biodisponibilidad de Co, Cr, Cu, Mn, Ni, Pb y Zn. El suelo SM1 estaba contaminado con Cr (283 µg g-1) y tenía concentraciones ligeramente elevadas (25-100 µg g-1) de Ni, Zn y Pb; el suelo SM2 estaba moderadamente contaminado en Cr (263 µg g-1), Cu (264 µg g-1), Pb (1433 µg g-1) y Zn (377 µg g-1). Los suelos fueron encalados hasta pH 6.0 con carbonato cálcico (SM1/Ca y SM2/Ca) o encalados y fertilizados con NPK (SM1/ NPK y SM2/ NPK). Los suelos sin enmienda fueron letales para A. serpyllifolium, las pla...
The HOMBRE (Holistic Management of Brownfield Regeneration) project seeks to aid both the prevent... more The HOMBRE (Holistic Management of Brownfield Regeneration) project seeks to aid both the prevention of sites from becoming brownfields (BFs) and the regeneration of existing BFs into usable sites. Work Package 5 of the HOMBRE project aims to improve solutions for long term land use of current and potential future BFs. To achieve this, WP5 looks to both the development of new, and improvement of existing, technologies for the regeneration of BFs into green end uses. The objective of this report is to fulfil HOMBRE deliverable 5.4, which has the aim of investigating and providing guidance on the operating windows of: 1. Biochar and other in situ stabilisation agents 2. Organic matter recycling These are examples of two important low input technology groups for regenerating BF, supporting specific soil functionality and risk management on site, as well as providing wider environmental benefits (e.g. carbon sequestration). This report provides an overview of existing literature regardi...
... combination of bioremediation and phytoremediation, or the phytostimulation of rhizosphere mi... more ... combination of bioremediation and phytoremediation, or the phytostimulation of rhizosphere microorganisms, is likely ... having a surfactant activity, which is favourable for phytoremediation purposes. Thus the degradation of several chlorinated pesticides has been reported to be ...
The efficiency of Alyssum serpyllifolium ssp. lusitanicum (Brassicaceae) for use in phytoextracti... more The efficiency of Alyssum serpyllifolium ssp. lusitanicum (Brassicaceae) for use in phytoextraction of polymetallic contaminated soils was evaluated. A. serpyllifolium was grown on two mine-spoil soils (MS1 and MS2): MS1 is contaminated with Cr (283 mg kg(-1)) and MS2 is moderately contaminated with Cr (263 mg kg(-1)), Cu (264 mg kg(-1)), Pb (1433 mg kg(-1)) and Zn (377 mg kg(-1)). Soils were limed to about pH 6.0 (MS1/Ca and MS2/Ca) or limed and amended with NPK fertilisers (MS1/NPK and MS2/NPK). Biomass was reduced on MS2/Ca due to Cu phytotoxicity. Fertilisation increased biomass by 10-fold on MS1/NPK, but root growth was reduced by 7-fold compared with MS1/Ca. Plants accumulated Mn, Ni and Zn in shoots, and both metal content and transportation were generally greater in MS2 than in MS1. Zinc bioaccumulation factors (BF, shoot([metal])/soil([metal])) were significantly greater in MS2 than in MS1. However, metal yields were greatest in plants grown on MS1/NPK. Concentrations of ED...
Vegetation and its associated microorganisms play an important role in the behaviour of soil cont... more Vegetation and its associated microorganisms play an important role in the behaviour of soil contaminants. One of the most important elements is root exudation, since it can affect the mobility, and therefore, the bioavailability of soil contaminants. In this study, we evaluated the influence of root exudates on the mobility of fuel derived compounds in contaminated soils. Samples of humic acid, montmorillonite, and an A horizon from an alumi-umbric Cambisol were contaminated with volatile contaminants present in fuel: oxygenates (MTBE and ETBE) and monoaromatic compounds (benzene, toluene, ethylbenzene and xylene). Natural root exudates obtained from Holcus lanatus and Cytisus striatus and ten artificial exudates (components frequently found in natural exudates) were added to the samples, individually and as a mixture, to evaluate their effects on contaminant mobility. Fuel compounds were analyzed by headspace-gas chromatography-mass spectrometry. In general, the addition of natural and artificial exudates increased the mobility of all contaminants in humic acid. In A horizon and montmorillonite, natural or artificial exudates (as a mixture) decreased the contaminant mobility. However, artificial exudates individually had different effects: carboxylic components increased and phenolic components decreased the contaminant mobility. These results established a base for developing and improving phytoremediation processes of fuel-contaminated soils.
ABSTRACT The aim of this study was to identify metal-tolerant plants with potential application i... more ABSTRACT The aim of this study was to identify metal-tolerant plants with potential application in phytoremediation strategies. For this we evaluated the distribution and chemical fractionation of heavy metals in soils and their accumulation or exclusion by native plant species growing in an abandoned Pb/Zn mine in NW Spain. Mine-soils (I = 0–20 cm, II = 20–40 cm) and shoots of the dominant plants were sampled at 39 sampling points in a (100 m × 100 m) regular grid at two sites (mine zone (MZ) and tailing ponds (TP)). Total metal contents in mine-soils presented a high heterogeneity and the principal contaminants were Cd, Hg, Pb and Zn (in agreement with the mineralogy of the site). Total concentrations varied from 2 to 95 mg Cd kg−1, 0.2 to 24.8 mg Hg kg−1, 46 to 6100 mg Pb kg−1, and 340 to 52,000 mg Zn kg−1. Soil metal distribution did not vary significantly with depth, but total and EDTA-extractable metal concentrations were higher in MZ than TP. On the other hand, the relative extractability of soil metals (EDTA-extractable concentration expressed as a % of total concentration) was higher in TP. The residual fraction was dominant for Co, Cr, Cu, and Ni, representing generally more than 50% of total concentration. Pb was preferentially associated with the oxidisable fraction, followed by the acid-extractable fraction. Both Cd and Zn were amply represented by the oxidisable, reducible and acid-extractable fractions. All the studied plant species were metal-tolerant (pseudometallophytes), although differences were found between species. Significant differences were found in plant accumulation of Cd and primarily, Zn. Cytisus scoparius and C. multiflorus were efficient metal-excluding species, and could be interesting candidates for phytostabilisation techniques and/or revegetation of heavily contaminated soils. Salix atrocinerea, presented significantly higher concentrations of Zn in its aerial biomass (543 ± 108 mg Zn kg−1) than the remaining species and bioconcentration factors (BCF) of up to 2.35 for Zn and 4.17 for Cd, respectively. This population could be interesting in the phytoextraction of low to moderately-contaminated soils.
Phytoremediation techniques are now considered to be promising alternatives to conventional techn... more Phytoremediation techniques are now considered to be promising alternatives to conventional techniques for the remediation of diffused or moderately contaminated soils. Despite their growing acceptance relatively few plant species have been studied for phytoremediation purposes. Further geobotanical surveys and plant screenings are necessary since these could lead to the identification of additional species with potential value for such applications. Serpentine areas could prove valuable sources of such plants. In this study heavy metal accumulation was determined in the flora associated with ultramafic and non-ultramafic soils of the Trás-os-Montes region of NE Portugal. Study sites were selected to represent a wide range of soil-forming rocks (serpentinized (S), ultrabasic (UB), basic (B) and acid (migmatite, M and schists, SC) rocks) and plant metal accumulation was related to soil metal bioavailability. Nine plant species (representing 7 families) were sampled including the Ni h...
Soil contamination by xenobiotic organic compounds is a serious problem in most industrialized co... more Soil contamination by xenobiotic organic compounds is a serious problem in most industrialized countries, causing acute and diffuse contamination of soil and waters on a global scale. Microbial transformation plays a major role in contaminant degradation of many persistent organic pollutants (POPs). However, microbial degradation can be limited by factors such as contaminant bioavailability, - adsorption and mass transfer, while
International Journal of Phytoremediation, Jan 1, 2009
In this study we determine culturable microbial densities (total heterotrophs, ammonifiers, amylo... more In this study we determine culturable microbial densities (total heterotrophs, ammonifiers, amylolytics and cellulolytics) and bacterial resistance to Co, Cr, and Ni in bulk and rhizosphere soils of three populations of the Ni-hyperaccumulator Alyssum serpyllifolium subsp. lusitanicum and the excluder Dactylis glomerata from ultramafic sites (two populations in Northeast (NE) Portugal (Samil (S), Morais (M)) and one population in Northwest (NW) Spain (Melide (L)). The relationship between bioavailable metal concentrations (H2O-soluble) and microbial densities were analysed. Significant differences in microbial densities and metal-resistance were observed between the two species and their three populations. The hyperaccumulator showed higher microbial densities (except cellulolytics) and a greater rhizosphere effect, but this was only observed in S and M populations. These populations of A. serpyllifolium also showed selective enrichment of Ni-tolerant bacteria at the rhizosphere where Ni solubility was enhanced (densities of Ni-resistant bacteria were positively correlated with H2O-soluble Ni). These rhizobacteria could solubilise Ni in the soil and potentially improve phytoextraction strategies.
We report the 4.76-Mb draft genome of Pantoea ananatis GB1, a Gram-negative bacterium of the fami... more We report the 4.76-Mb draft genome of Pantoea ananatis GB1, a Gram-negative bacterium of the family Enterobacteriaceae, isolated from the roots of poplars planted for phytoremediation of a diesel-contaminated plume at the Ford Motor Company site in Genk, Belgium. Strain GB1 promotes plant growth in various hosts and metabolizes hydrocarbons.
Volatile fuel compounds such as fuel oxygenates (FO) (MTBE and ETBE) and BTEX (benzene, toluene, ... more Volatile fuel compounds such as fuel oxygenates (FO) (MTBE and ETBE) and BTEX (benzene, toluene, ethylbenzene and xylene) are some of the most soluble components of fuel. Characterizing the leaching potential of these compounds is essential for predicting their mobility through the soil profile and assessing the risk of groundwater contamination. Plant root exudates can play an important role in the modification of contaminant mobility in soil-plant systems, and such effects should also be considered in leaching studies. Artificially spiked samples of A and B horizons from an alumi-umbric Cambisol were leached in packed-columns and batch experiments using Milli-Q water and plant root exudates as leaching agents. The leaching potential and rate were strongly influenced by soil-contaminant interactions and by the presence of root exudates. Organic matter in A horizon preferably sorbed the most non-polar contaminants, lowering their leaching potential, and this effect was enhanced by the presence of root exudates. On the other hand, the inorganic components of the B horizon, showed a greater affinity for polar molecules, and the presence of root exudates enhanced the desorption of the contaminants. Column experiments resulted in a more realistic protocol than batch tests for predicting the leaching potential of volatile organic compounds in dissimilar soils.
Factors associated with soil acidity are considered to be limiting for plants in many parts of th... more Factors associated with soil acidity are considered to be limiting for plants in many parts of the world. This work was undertaken to investigate the role of the toxicity of hydrogen (H(+)) which seems to have been underconsidered by ecologists as an explanation of the reduced plant growth observed in very acid soils. Racial differences are reported in plant growth response to increasing acidity in the grass Holcus lanatus L. (Yorkshire-fog) and the tree Betula pendula Roth (Silver Birch). Soils and seeds were collected from four Scottish sites which covered a range of soils from acid (organic and mineral) to more base-rich. The sites and their pH (1:2.5 fresh soil:0.01 M CaCl(2)) were: Flanders Moss (FM), pH 3.2+/-0.03; Kippenrait Glen (KP), pH 4.8+/- 0.05; Kinloch Rannoch (KR), pH 6.1+/-0.16; and Sheriffmuir (SMM), pH 4.3+/-0.11. The growth rates of two races of H. lanatus, FM and KP, and three races of B. pendula (SMM, KP and KR) were measured in nutrient solution cultures at pH 2.0 (H. lanatus only), 3.0, 4.0, 5.0, and 5.6. Results showed races from acid organic soils (FM) were H(+)-tolerant while those from acid mineral soils (SMM) were Al(3+)-tolerant but not necessarily H(+)-tolerant. These results confirmed that populations were separately adapted to H(+) or Al(3+) toxicity and this was dependent upon the soil characteristics at their site of collection. The fact of plant adaptation to H(+) toxicity supports the view that this is an important factor in very acid soils.
Se evalúa la eficiencia de Serpyllifolium ssp. Lusitanicum (Brassicaceae), un hiperacumulador de ... more Se evalúa la eficiencia de Serpyllifolium ssp. Lusitanicum (Brassicaceae), un hiperacumulador de Ni que crece en los suelos serpentiníticos de la región de Tras Os Montes (NE Portugal), para su uso en fitoextracción de metales en suelos de mina. Para ello se hizo un ensayo de invernadero con Alyssum serpyllifolium y dos suelos de mina (SM1 y SM2). Se estudió la capacidad de esta especie para acceder a diferentes fracciones metálicas del suelo, así como los cambios que inducía sobre la biodisponibilidad de Co, Cr, Cu, Mn, Ni, Pb y Zn. El suelo SM1 estaba contaminado con Cr (283 µg g-1) y tenía concentraciones ligeramente elevadas (25-100 µg g-1) de Ni, Zn y Pb; el suelo SM2 estaba moderadamente contaminado en Cr (263 µg g-1), Cu (264 µg g-1), Pb (1433 µg g-1) y Zn (377 µg g-1). Los suelos fueron encalados hasta pH 6.0 con carbonato cálcico (SM1/Ca y SM2/Ca) o encalados y fertilizados con NPK (SM1/ NPK y SM2/ NPK). Los suelos sin enmienda fueron letales para A. serpyllifolium, las pla...
The HOMBRE (Holistic Management of Brownfield Regeneration) project seeks to aid both the prevent... more The HOMBRE (Holistic Management of Brownfield Regeneration) project seeks to aid both the prevention of sites from becoming brownfields (BFs) and the regeneration of existing BFs into usable sites. Work Package 5 of the HOMBRE project aims to improve solutions for long term land use of current and potential future BFs. To achieve this, WP5 looks to both the development of new, and improvement of existing, technologies for the regeneration of BFs into green end uses. The objective of this report is to fulfil HOMBRE deliverable 5.4, which has the aim of investigating and providing guidance on the operating windows of: 1. Biochar and other in situ stabilisation agents 2. Organic matter recycling These are examples of two important low input technology groups for regenerating BF, supporting specific soil functionality and risk management on site, as well as providing wider environmental benefits (e.g. carbon sequestration). This report provides an overview of existing literature regardi...
... combination of bioremediation and phytoremediation, or the phytostimulation of rhizosphere mi... more ... combination of bioremediation and phytoremediation, or the phytostimulation of rhizosphere microorganisms, is likely ... having a surfactant activity, which is favourable for phytoremediation purposes. Thus the degradation of several chlorinated pesticides has been reported to be ...
The efficiency of Alyssum serpyllifolium ssp. lusitanicum (Brassicaceae) for use in phytoextracti... more The efficiency of Alyssum serpyllifolium ssp. lusitanicum (Brassicaceae) for use in phytoextraction of polymetallic contaminated soils was evaluated. A. serpyllifolium was grown on two mine-spoil soils (MS1 and MS2): MS1 is contaminated with Cr (283 mg kg(-1)) and MS2 is moderately contaminated with Cr (263 mg kg(-1)), Cu (264 mg kg(-1)), Pb (1433 mg kg(-1)) and Zn (377 mg kg(-1)). Soils were limed to about pH 6.0 (MS1/Ca and MS2/Ca) or limed and amended with NPK fertilisers (MS1/NPK and MS2/NPK). Biomass was reduced on MS2/Ca due to Cu phytotoxicity. Fertilisation increased biomass by 10-fold on MS1/NPK, but root growth was reduced by 7-fold compared with MS1/Ca. Plants accumulated Mn, Ni and Zn in shoots, and both metal content and transportation were generally greater in MS2 than in MS1. Zinc bioaccumulation factors (BF, shoot([metal])/soil([metal])) were significantly greater in MS2 than in MS1. However, metal yields were greatest in plants grown on MS1/NPK. Concentrations of ED...
Vegetation and its associated microorganisms play an important role in the behaviour of soil cont... more Vegetation and its associated microorganisms play an important role in the behaviour of soil contaminants. One of the most important elements is root exudation, since it can affect the mobility, and therefore, the bioavailability of soil contaminants. In this study, we evaluated the influence of root exudates on the mobility of fuel derived compounds in contaminated soils. Samples of humic acid, montmorillonite, and an A horizon from an alumi-umbric Cambisol were contaminated with volatile contaminants present in fuel: oxygenates (MTBE and ETBE) and monoaromatic compounds (benzene, toluene, ethylbenzene and xylene). Natural root exudates obtained from Holcus lanatus and Cytisus striatus and ten artificial exudates (components frequently found in natural exudates) were added to the samples, individually and as a mixture, to evaluate their effects on contaminant mobility. Fuel compounds were analyzed by headspace-gas chromatography-mass spectrometry. In general, the addition of natural and artificial exudates increased the mobility of all contaminants in humic acid. In A horizon and montmorillonite, natural or artificial exudates (as a mixture) decreased the contaminant mobility. However, artificial exudates individually had different effects: carboxylic components increased and phenolic components decreased the contaminant mobility. These results established a base for developing and improving phytoremediation processes of fuel-contaminated soils.
ABSTRACT The aim of this study was to identify metal-tolerant plants with potential application i... more ABSTRACT The aim of this study was to identify metal-tolerant plants with potential application in phytoremediation strategies. For this we evaluated the distribution and chemical fractionation of heavy metals in soils and their accumulation or exclusion by native plant species growing in an abandoned Pb/Zn mine in NW Spain. Mine-soils (I = 0–20 cm, II = 20–40 cm) and shoots of the dominant plants were sampled at 39 sampling points in a (100 m × 100 m) regular grid at two sites (mine zone (MZ) and tailing ponds (TP)). Total metal contents in mine-soils presented a high heterogeneity and the principal contaminants were Cd, Hg, Pb and Zn (in agreement with the mineralogy of the site). Total concentrations varied from 2 to 95 mg Cd kg−1, 0.2 to 24.8 mg Hg kg−1, 46 to 6100 mg Pb kg−1, and 340 to 52,000 mg Zn kg−1. Soil metal distribution did not vary significantly with depth, but total and EDTA-extractable metal concentrations were higher in MZ than TP. On the other hand, the relative extractability of soil metals (EDTA-extractable concentration expressed as a % of total concentration) was higher in TP. The residual fraction was dominant for Co, Cr, Cu, and Ni, representing generally more than 50% of total concentration. Pb was preferentially associated with the oxidisable fraction, followed by the acid-extractable fraction. Both Cd and Zn were amply represented by the oxidisable, reducible and acid-extractable fractions. All the studied plant species were metal-tolerant (pseudometallophytes), although differences were found between species. Significant differences were found in plant accumulation of Cd and primarily, Zn. Cytisus scoparius and C. multiflorus were efficient metal-excluding species, and could be interesting candidates for phytostabilisation techniques and/or revegetation of heavily contaminated soils. Salix atrocinerea, presented significantly higher concentrations of Zn in its aerial biomass (543 ± 108 mg Zn kg−1) than the remaining species and bioconcentration factors (BCF) of up to 2.35 for Zn and 4.17 for Cd, respectively. This population could be interesting in the phytoextraction of low to moderately-contaminated soils.
Phytoremediation techniques are now considered to be promising alternatives to conventional techn... more Phytoremediation techniques are now considered to be promising alternatives to conventional techniques for the remediation of diffused or moderately contaminated soils. Despite their growing acceptance relatively few plant species have been studied for phytoremediation purposes. Further geobotanical surveys and plant screenings are necessary since these could lead to the identification of additional species with potential value for such applications. Serpentine areas could prove valuable sources of such plants. In this study heavy metal accumulation was determined in the flora associated with ultramafic and non-ultramafic soils of the Trás-os-Montes region of NE Portugal. Study sites were selected to represent a wide range of soil-forming rocks (serpentinized (S), ultrabasic (UB), basic (B) and acid (migmatite, M and schists, SC) rocks) and plant metal accumulation was related to soil metal bioavailability. Nine plant species (representing 7 families) were sampled including the Ni h...
Soil contamination by xenobiotic organic compounds is a serious problem in most industrialized co... more Soil contamination by xenobiotic organic compounds is a serious problem in most industrialized countries, causing acute and diffuse contamination of soil and waters on a global scale. Microbial transformation plays a major role in contaminant degradation of many persistent organic pollutants (POPs). However, microbial degradation can be limited by factors such as contaminant bioavailability, - adsorption and mass transfer, while
International Journal of Phytoremediation, Jan 1, 2009
In this study we determine culturable microbial densities (total heterotrophs, ammonifiers, amylo... more In this study we determine culturable microbial densities (total heterotrophs, ammonifiers, amylolytics and cellulolytics) and bacterial resistance to Co, Cr, and Ni in bulk and rhizosphere soils of three populations of the Ni-hyperaccumulator Alyssum serpyllifolium subsp. lusitanicum and the excluder Dactylis glomerata from ultramafic sites (two populations in Northeast (NE) Portugal (Samil (S), Morais (M)) and one population in Northwest (NW) Spain (Melide (L)). The relationship between bioavailable metal concentrations (H2O-soluble) and microbial densities were analysed. Significant differences in microbial densities and metal-resistance were observed between the two species and their three populations. The hyperaccumulator showed higher microbial densities (except cellulolytics) and a greater rhizosphere effect, but this was only observed in S and M populations. These populations of A. serpyllifolium also showed selective enrichment of Ni-tolerant bacteria at the rhizosphere where Ni solubility was enhanced (densities of Ni-resistant bacteria were positively correlated with H2O-soluble Ni). These rhizobacteria could solubilise Ni in the soil and potentially improve phytoextraction strategies.
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Papers by Petra Kidd