Abstract
The bioavailability of metals in soil is often cited as a limiting factor of phytoextraction (or phytomining). Bacterial metabolites, such as organic acids, siderophores, or biosurfactants, have been shown to mobilize metals, and their use to improve metal extraction has been proposed. In this study, the weathering capacities of, and Ni mobilization by, bacterial strains were evaluated. Minimal medium containing ground ultramafic rock was inoculated with either of two Arthrobacter strains: LA44 (indole acetic acid [IAA] producer) or SBA82 (siderophore producer, PO4 solubilizer, and IAA producer). Trace elements and organic compounds were determined in aliquots taken at different time intervals after inoculation. Trace metal fractionation was carried out on the remaining rock at the end of the experiment. The results suggest that the strains act upon different mineral phases. LA44 is a more efficient Ni mobilizer, apparently solubilizing Ni associated with Mn oxides, and this appeared to be related to oxalate production. SBA82 also leads to release of Ni and Mn, albeit to a much lower extent. In this case, the concurrent mobilization of Fe and Si indicates preferential weathering of Fe oxides and serpentine minerals, possibly related to the siderophore production capacity of the strain. The same bacterial strains were tested in a soil-plant system: the Ni hyperaccumulator Alyssum serpyllifolium subsp. malacitanum was grown in ultramafic soil in a rhizobox system and inoculated with each bacterial strain. At harvest, biomass production and shoot Ni concentrations were higher in plants from inoculated pots than from noninoculated pots. Ni yield was significantly enhanced in plants inoculated with LA44. These results suggest that Ni-mobilizing inoculants could be useful for improving Ni uptake by hyperaccumulator plants.
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Claims 6
Claim · model-written summary
Biomass production of Alyssum serpyllifolium subsp. malacitanum was higher in plants from inoculated pots than from noninoculated pots at harvest.
- Taxon
- Alyssum serpyllifolium subsp. malacitanum
Alyssum malacitanume0 - Treatment
- inoculatede0
- Interactor
- Arthrobacter
Arthrobactere2other - Outcome
- biomass productione1
- Direction
- highere1
- Comparator
- noninoculated potse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the Ni hyperaccumulator Alyssum serpyllifolium subsp. malacitanum was grown in ultramafic soil in a rhizobox system and inoculated with each bacterial strain”
e1“At harvest, biomass production and shoot Ni concentrations were higher in plants from inoculated pots than from noninoculated pots”
e2“either of two Arthrobacter strains”
Claim · model-written summary
Shoot Ni concentrations of Alyssum serpyllifolium subsp. malacitanum were higher in plants from inoculated pots than from noninoculated pots at harvest.
- Taxon
- Alyssum serpyllifolium subsp. malacitanumAlyssum malacitanume0
- Treatment
- inoculatede0
- Interactor
- ArthrobacterArthrobactere2other
- Outcome
- shoot Ni concentrationse1
- Direction
- highere1
- Comparator
- noninoculated potse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the Ni hyperaccumulator Alyssum serpyllifolium subsp. malacitanum was grown in ultramafic soil in a rhizobox system and inoculated with each bacterial strain”
e1“At harvest, biomass production and shoot Ni concentrations were higher in plants from inoculated pots than from noninoculated pots”
e2“either of two Arthrobacter strains”
Claim · model-written summary
Ni yield was significantly enhanced in Alyssum plants inoculated with strain LA44.
- Taxon
- Alyssum serpyllifolium subsp. malacitanumAlyssum malacitanume0
- Treatment
- inoculated with LA44e1
- Interactor
- LA44e1other
- Outcome
- Ni yielde1
- Direction
- enhancede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the Ni hyperaccumulator Alyssum serpyllifolium subsp. malacitanum was grown in ultramafic soil in a rhizobox system and inoculated with each bacterial strain”
e1“Ni yield was significantly enhanced in plants inoculated with LA44”
Claim · model-written summary
Arthrobacter strain LA44 was the more efficient Ni mobilizer from ultramafic rock, apparently solubilizing Ni associated with Mn oxides.
- Taxon
- ArthrobacterArthrobactere2
- Outcome
- more efficient Ni mobilizere0
- Qualifier
- apparently solubilizing Ni associated with Mn oxidese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“LA44 is a more efficient Ni mobilizer, apparently solubilizing Ni associated with Mn oxides”
e2“either of two Arthrobacter strains”
Claim · model-written summary
Arthrobacter strain SBA82 also released Ni and Mn from ultramafic rock, but to a much lower extent.
- Taxon
- ArthrobacterArthrobactere2
- Outcome
- release of Ni and Mne0
- Qualifier
- much lower extente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SBA82 also leads to release of Ni and Mn, albeit to a much lower extent”
e2“either of two Arthrobacter strains”
Claim · model-written summary
The authors conclude that Ni-mobilizing inoculants could be useful for improving Ni uptake by hyperaccumulator plants.
Verbatim
e0“Ni-mobilizing inoculants could be useful for improving Ni uptake by hyperaccumulator plants”