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Kristina Lindstrom - One of the best experts on this subject based on the ideXlab platform.
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Genome sequencing of two Neorhizobium Galegae strains reveals a noeT gene responsible for the unusual acetylation of the nodulation factors.
BMC genomics, 2014Co-Authors: Janina Österman, Joanne Marsh, Pia Laine, Zhen Zeng, Edward Alatalo, John T. Sullivan, J. Peter W. Young, Jane Thomas-oates, Lars Paulin, Kristina LindstromAbstract:Background The species Neorhizobium Galegae comprises two symbiovars that induce nodules on Galega plants. Strains of both symbiovars, orientalis and officinalis, induce nodules on the same plant species, but fix nitrogen only in their own host species. The mechanism behind this strict host specificity is not yet known. In this study, genome sequences of representatives of the two symbiovars were produced, providing new material for studying properties of N. Galegae, with a special interest in genomic differences that may play a role in host specificity.
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alleviation of salt stress of symbiotic Galega officinalis l goat s rue by co inoculation of rhizobium with root colonizing pseudomonas
Plant and Soil, 2013Co-Authors: Kristina Lindstrom, Dilfuza Egamberdieva, Gabriela Berg, Leena A RasanenAbstract:Background and aims Salt stress is an increasing problem in agricultural soils in many parts of the world, and salt tolerant cropping systems are in great demand. We investigated the effect of co-inoculation of Galega officinalis with Rhizobium Galegae and two plant growth promoting Pseudomonas species on plant growth, nodulation, and N content under salt stress.
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Co-inoculation of Pseudomonas spp. with Rhizobium improves growth and symbiotic performance of fodder Galega (Galega orientalis Lam.)
European Journal of Soil Biology, 2010Co-Authors: Dilfuza Egamberdieva, Kristina Lindstrom, Gabriele Berg, Leena RäsänenAbstract:Abstract The effect of Rhizobium Galegae alone and in combination with root colonising Pseudomonas strains on the growth of fodder Galega ( Galega orientalis Lam.) was studied under greenhouse conditions in potting soil containing low levels of nitrogen. Eight weeks after sowing combined inoculations of fodder Galega with R. Galegae bv. orientalis HAMBI 540 and Pseudomonas trivialis 3Re27 or Pseudomonas extremorientalis TSAU20 had increased shoot and root dry matter, as compared with inoculation with R. Galegae HAMBI 540 alone. Both Pseudomonas strains produced indole-3-acetic acid (IAA) in culture but R. Galegae did not. While the cellulase producing strain P. trivialis 3Re27 was able to significantly increase nodule numbers and nitrogen content of the co-inoculated plants, the cellulase-negative P. extremorientalis TSAU20 showed no significant stimulation of nodule numbers and nitrogen content in roots. We conclude that P. trivialis 3Re27 improve rhizobia–legume interactions, acting as “rhizobium helper bacteria”. The production of IAA and/or cellulase by Pseudomonas strains may contribute to such a positive effect.
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tol plasmid transfer during bacterial conjugation in vitro and rhizoremediation of oil compounds in vivo
Environmental Pollution, 2007Co-Authors: Minna M. Jussila, Leena Suominen, Ji Zhao, Kristina LindstromAbstract:Molecular profiling methods for horizontal transfer of aromatics-degrading plasmids were developed and applied during rhizoremediation in vivo and conjugations in vitro. pWW0 was conjugated from Pseudomonas to Rhizobium. The xylE gene was detected both in Rhizobium Galegae bv. officinalis and bv. orientalis, but it was neither stably maintained in orientalis nor functional in officinalis. TOL plasmids were a major group of catabolic plasmids among the bacterial strains isolated from the oil-contaminated rhizosphere of Galega orientalis. A new finding was that some Pseudomonas migulae and Pseudomonas oryzihabitans strains harbored a TOL plasmid with both pWW0- and pDK1-type xylE gene. P. oryzihabitans 29 had received the archetypal TOL plasmid pWW0 from Pseudomonas putida PaW85. As an application for environmental biotechnology, the biodegradation potential of oil-polluted soil and the success of bioremediation could be estimated by monitoring changes not only in the type and amount but also in transfer of degradation plasmids.
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rhizosphere effect of Galega orientalis in oil contaminated soil
Soil Biology & Biochemistry, 2006Co-Authors: Anna H Kaksonen, Minna M. Jussila, Kristina Lindstrom, Leena SuominenAbstract:Abstract Randomized lysimeters in an oil-contaminated field contained the following treatments: (1) Galega orientalis seeds inoculated with Rhizobium Galegae HAMBI 540, (2) bioaugmentation with Pseudomonas putida PaW85, and (3) R. Galegae -inoculated G. orientalis seeds plus bioaugmentation with P. putida PaW85. The bacterial abundance and diversity were analysed in composite samples after one growing season. A total of 208 m-toluate tolerating bacteria were isolated and screened with m-toluate tolerance and utilization tests, and the catechol test. Seventy-nine isolates were characterized with (GTG)5-PCR genomic fingerprinting and 16S rRNA gene PCR-RFLP ribotyping. Only 10% of the isolated strains were able to degrade m-toluate. Most of the m-toluate utilizing bacteria were catechol positive indicating the existence of a TOL plasmid. Rhizosphere effect of G. orientalis was manifested in oil-contaminated soil. G. orientalis and Pseudomonas bioaugmentation increased the amount of bacteria in oil-contaminated soil. G. orientalis especially together with Pseudomonas bioaugmentation increased the numbers of m-toluate utilizing and catechol positive bacteria in the soil samples indicating an increase in degradation potential. The rhizosphere of G. orientalis increased also the diversity of bacteria. More ribotypes were found in soils treated with G. orientalis and P. putida PaW85 compared to the untreated soil, but the diversity of the m-toluate utilizing bacteria did not significantly increase.
Philippe De Lajudie - One of the best experts on this subject based on the ideXlab platform.
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Characterisation of wild legume nodulating bacteria (LNB) in the infra-arid zone of Tunisia.
Systematic and Applied Microbiology, 2004Co-Authors: Frédéric Zakhia, H. Jeder, Odile Domergue, Jean-claude Cleyet-marel, Bernard Dreyfus, Monique Gillis, Anne Willems, Philippe De LajudieAbstract:Summary We report on the isolation and the characterization of nitrogen-fixing root nodule bacteria isolated from natural legumes in a region of South Tunisia corresponding to the infra-arid climatic zone. A collection of 60 new bacterial root nodule isolates were obtained from 19 legume species belonging to the genera Acacia, Anthyllis, Argyrolobium, Astragalus, Calycotome, Coronilla, Ebenus, Genista, Hedysarum, Hippocrepis, Lathyrus, Lotus, Medicago, Ononis. The isolates were characterised by (1) comparative 16S ARDRA using 7 enzymes, (2) total cell protein SDS-PAGE analysis and (3) 16S rDNA sequencing. The results show that these isolates are diverse and belong to the genera Rhizobium, Sinorhizobium, Mesorhizobium and Bradyrhizobium . Bradyrhizobium were further characterised by 16S-23S rDNA IGS sequencing. Surprisingly strains nodulating Astragalus cruciatus, Lotus creticus and Anthyllis henoniana were identified as Rhizobium Galegae , a species recorded only as endosymbiont of Galega officinalis and G. orientalis in northern regions so far.
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Characterisation of wild legume nodulating bacteria (LNB) in the infra-arid zone of Tunisia.
Systematic and Applied Microbiology, 2004Co-Authors: Frédéric Zakhia, H. Jeder, Odile Domergue, Jean-claude Cleyet-marel, Bernard Dreyfus, Monique Gillis, Anne Willems, Philippe De LajudieAbstract:Summary We report on the isolation and the characterization of nitrogen-fixing root nodule bacteria isolated from natural legumes in a region of South Tunisia corresponding to the infra-arid climatic zone. A collection of 60 new bacterial root nodule isolates were obtained from 19 legume species belonging to the genera Acacia, Anthyllis, Argyrolobium, Astragalus, Calycotome, Coronilla, Ebenus, Genista, Hedysarum, Hippocrepis, Lathyrus, Lotus, Medicago, Ononis. The isolates were characterised by (1) comparative 16S ARDRA using 7 enzymes, (2) total cell protein SDS-PAGE analysis and (3) 16S rDNA sequencing. The results show that these isolates are diverse and belong to the genera Rhizobium, Sinorhizobium, Mesorhizobium and Bradyrhizobium . Bradyrhizobium were further characterised by 16S-23S rDNA IGS sequencing. Surprisingly strains nodulating Astragalus cruciatus, Lotus creticus and Anthyllis henoniana were identified as Rhizobium Galegae , a species recorded only as endosymbiont of Galega officinalis and G. orientalis in northern regions so far.
Leena Suominen - One of the best experts on this subject based on the ideXlab platform.
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tol plasmid transfer during bacterial conjugation in vitro and rhizoremediation of oil compounds in vivo
Environmental Pollution, 2007Co-Authors: Minna M. Jussila, Leena Suominen, Ji Zhao, Kristina LindstromAbstract:Molecular profiling methods for horizontal transfer of aromatics-degrading plasmids were developed and applied during rhizoremediation in vivo and conjugations in vitro. pWW0 was conjugated from Pseudomonas to Rhizobium. The xylE gene was detected both in Rhizobium Galegae bv. officinalis and bv. orientalis, but it was neither stably maintained in orientalis nor functional in officinalis. TOL plasmids were a major group of catabolic plasmids among the bacterial strains isolated from the oil-contaminated rhizosphere of Galega orientalis. A new finding was that some Pseudomonas migulae and Pseudomonas oryzihabitans strains harbored a TOL plasmid with both pWW0- and pDK1-type xylE gene. P. oryzihabitans 29 had received the archetypal TOL plasmid pWW0 from Pseudomonas putida PaW85. As an application for environmental biotechnology, the biodegradation potential of oil-polluted soil and the success of bioremediation could be estimated by monitoring changes not only in the type and amount but also in transfer of degradation plasmids.
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rhizosphere effect of Galega orientalis in oil contaminated soil
Soil Biology & Biochemistry, 2006Co-Authors: Anna H Kaksonen, Minna M. Jussila, Kristina Lindstrom, Leena SuominenAbstract:Abstract Randomized lysimeters in an oil-contaminated field contained the following treatments: (1) Galega orientalis seeds inoculated with Rhizobium Galegae HAMBI 540, (2) bioaugmentation with Pseudomonas putida PaW85, and (3) R. Galegae -inoculated G. orientalis seeds plus bioaugmentation with P. putida PaW85. The bacterial abundance and diversity were analysed in composite samples after one growing season. A total of 208 m-toluate tolerating bacteria were isolated and screened with m-toluate tolerance and utilization tests, and the catechol test. Seventy-nine isolates were characterized with (GTG)5-PCR genomic fingerprinting and 16S rRNA gene PCR-RFLP ribotyping. Only 10% of the isolated strains were able to degrade m-toluate. Most of the m-toluate utilizing bacteria were catechol positive indicating the existence of a TOL plasmid. Rhizosphere effect of G. orientalis was manifested in oil-contaminated soil. G. orientalis and Pseudomonas bioaugmentation increased the amount of bacteria in oil-contaminated soil. G. orientalis especially together with Pseudomonas bioaugmentation increased the numbers of m-toluate utilizing and catechol positive bacteria in the soil samples indicating an increase in degradation potential. The rhizosphere of G. orientalis increased also the diversity of bacteria. More ribotypes were found in soils treated with G. orientalis and P. putida PaW85 compared to the untreated soil, but the diversity of the m-toluate utilizing bacteria did not significantly increase.
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potential of the Galega rhizobium Galegae system for bioremediation of oil contaminated soil
Food Technology and Biotechnology, 2003Co-Authors: Kristina Lindstrom, Jyrki Pitkajarvi, Minna M. Jussila, Katri Mäkeläinen, Hannamari Hintsa, Anna H Kaksonen, Lenna Mokelke, Leena SuominenAbstract:Summary Bioremediation potential of the nitrogen-fixing leguminous plant Galega orientalis Lam. and its microsymbiont Rhizobium Galegae was evaluated in microcosm and mesocosm scale in oil and BTEX (benzene, toluene, ethylbenzene, xylene) contaminated soils, with m-toluate serving as a model for the latter group. G. orientalis and Rhizobium Galegae remained viable in m-toluate fractions up to 3000 ppm. Plant growth and nodulation were inhibited in 500 ppm m-toluate, but were restored when plants were transferred to clean medium. In soil, G. orientalis nodulated and showed good growth in 2000 ppm m-toluate as well as in diesel-contaminated soil in the field, where the plant was stimulating bacterial growth in the rhizosphere. A collection of 52 indigenous m-toluate-tolerating bacteria isolated from oil-contaminated rhizosphere of G. orientalis was characterised and identified by classical and molecular biological methods. 16SrDNA PCR-RFLP and (GTG)5-PCR genomic fingerprinting combined with partial sequencing indicated the presence of five major lineages of the Bacteria domain. A TOL plasmid-specific xylE-PCR was developed in order to detect both active and potential degraders of m-toluate. The ability to degrade m-toluate in the presence of the gene xylE was detected only within the genus Pseudomonas. The isolates were tested for capacity to grow on m-toluate as their sole carbon and energy source. In laboratory experiments, the best rhizosphere isolates performed equally well to the positive control strain and are good candidates for inoculant production in the future. They have been tagged with marker genes for further studies on colonisation and persistence.
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activation of the noda promoter by the nodd genes of rhizobium Galegae induced by synthetic flavonoids or Galega orientalis root exudate
Fems Microbiology Letters, 2003Co-Authors: Leena Suominen, Christophe Roos, Reijo Luukkainen, Kristina LindstromAbstract:Abstract Rhizobial nodD genes produce transcriptional regulators that, together with appropriate inducer compounds, activate the other symbiotic nodulation ( nod ) genes and initiate the nodule formation process. Two nodD homologues, nodD 1 and nodD 2, are present in the Rhizobium Galegae strain HAMBI 1174. In this work we analysed their ability to induce the nodA promoter with synthetic inducers known to activate nod genes in other rhizobia. According to phylogenetic analysis, the inducer-specific carboxy-terminal part of the R. Galegae nodD protein sequence groups together with those of Rhizobium leguminosarum and Sinorhizobium meliloti . However, the respective inducer compounds for their NodD proteins are not highly effective with R. Galegae nodD products. The best inducer discovered with R. Galegae nodD 1 was the root exudate of the host plant of R. Galegae , Galega orientalis . HPLC analyses revealed the presence of many divergent flavonoid compounds in the G. orientalis root exudate. The most effective HPLC fractions induced R. Galegae nodD 1 up to the level obtained by intact G. orientalis root exudate while apigenin and luteolin, which were also present in the root exudate, were only moderate inducers. A UV-Vis diode array spectrum of the most active peak indicated that the main inducer present in the G. orientalis root exudate is an unidentified chalcone-type compound. In the Galega – R. Galegae interaction the first recognition between the NodD protein and the flavonoid inducer secreted from the roots of Galega is specific for these organisms, and thus partly responsible of the strict host specificity of this symbiosis.
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evaluation of the Galega rhizobium Galegae system for the bioremediation of oil contaminated soil
Environmental Pollution, 2000Co-Authors: Leena Suominen, Minna M. Jussila, Katri Mäkeläinen, Martin Romantschuk, Kristina LindstromAbstract:The bioremediation potential of a nitrogen-fixing leguminous plant, Galega orientalis, and its microsymbiont Rhizobium Galegae was evaluated in BTX (benzene, toluene, xylene)-contaminated soils in microcosm and mesocosm scale. To measure the intrinsic tolerance of the organisms to m-toluate, a model compound representing BTX, G. orientalis and R. Galegae were cultivated under increasing concentrations of m-toluate alone and in association with Pseudomonas putida pWWO, a bacterial strain able to degrade toluene-derived compounds. The test plants and rhizobia remained viable in m-toluate concentrations as high as 3000 ppm. Plant growth was inhibited in concentrations higher than 500 ppm, but restituted when plants were transferred into m-toluate-free medium. Nodulation was blocked under the influence of m-toluate, but was restored after the plants were transferred into the non-contaminated media. In the mesocosm assay the Galega plants showed good growth, nodulation and nitrogen fixation, and developed a strong rhizosphere in soils contaminated with oil or spiked with 2000 ppm m-toluate. Thus, this legume system has good potential for use on oil-contaminated sites
Frédéric Zakhia - One of the best experts on this subject based on the ideXlab platform.
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Characterisation of wild legume nodulating bacteria (LNB) in the infra-arid zone of Tunisia.
Systematic and Applied Microbiology, 2004Co-Authors: Frédéric Zakhia, H. Jeder, Odile Domergue, Jean-claude Cleyet-marel, Bernard Dreyfus, Monique Gillis, Anne Willems, Philippe De LajudieAbstract:Summary We report on the isolation and the characterization of nitrogen-fixing root nodule bacteria isolated from natural legumes in a region of South Tunisia corresponding to the infra-arid climatic zone. A collection of 60 new bacterial root nodule isolates were obtained from 19 legume species belonging to the genera Acacia, Anthyllis, Argyrolobium, Astragalus, Calycotome, Coronilla, Ebenus, Genista, Hedysarum, Hippocrepis, Lathyrus, Lotus, Medicago, Ononis. The isolates were characterised by (1) comparative 16S ARDRA using 7 enzymes, (2) total cell protein SDS-PAGE analysis and (3) 16S rDNA sequencing. The results show that these isolates are diverse and belong to the genera Rhizobium, Sinorhizobium, Mesorhizobium and Bradyrhizobium . Bradyrhizobium were further characterised by 16S-23S rDNA IGS sequencing. Surprisingly strains nodulating Astragalus cruciatus, Lotus creticus and Anthyllis henoniana were identified as Rhizobium Galegae , a species recorded only as endosymbiont of Galega officinalis and G. orientalis in northern regions so far.
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Characterisation of wild legume nodulating bacteria (LNB) in the infra-arid zone of Tunisia.
Systematic and Applied Microbiology, 2004Co-Authors: Frédéric Zakhia, H. Jeder, Odile Domergue, Jean-claude Cleyet-marel, Bernard Dreyfus, Monique Gillis, Anne Willems, Philippe De LajudieAbstract:Summary We report on the isolation and the characterization of nitrogen-fixing root nodule bacteria isolated from natural legumes in a region of South Tunisia corresponding to the infra-arid climatic zone. A collection of 60 new bacterial root nodule isolates were obtained from 19 legume species belonging to the genera Acacia, Anthyllis, Argyrolobium, Astragalus, Calycotome, Coronilla, Ebenus, Genista, Hedysarum, Hippocrepis, Lathyrus, Lotus, Medicago, Ononis. The isolates were characterised by (1) comparative 16S ARDRA using 7 enzymes, (2) total cell protein SDS-PAGE analysis and (3) 16S rDNA sequencing. The results show that these isolates are diverse and belong to the genera Rhizobium, Sinorhizobium, Mesorhizobium and Bradyrhizobium . Bradyrhizobium were further characterised by 16S-23S rDNA IGS sequencing. Surprisingly strains nodulating Astragalus cruciatus, Lotus creticus and Anthyllis henoniana were identified as Rhizobium Galegae , a species recorded only as endosymbiont of Galega officinalis and G. orientalis in northern regions so far.
Minna M. Jussila - One of the best experts on this subject based on the ideXlab platform.
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tol plasmid transfer during bacterial conjugation in vitro and rhizoremediation of oil compounds in vivo
Environmental Pollution, 2007Co-Authors: Minna M. Jussila, Leena Suominen, Ji Zhao, Kristina LindstromAbstract:Molecular profiling methods for horizontal transfer of aromatics-degrading plasmids were developed and applied during rhizoremediation in vivo and conjugations in vitro. pWW0 was conjugated from Pseudomonas to Rhizobium. The xylE gene was detected both in Rhizobium Galegae bv. officinalis and bv. orientalis, but it was neither stably maintained in orientalis nor functional in officinalis. TOL plasmids were a major group of catabolic plasmids among the bacterial strains isolated from the oil-contaminated rhizosphere of Galega orientalis. A new finding was that some Pseudomonas migulae and Pseudomonas oryzihabitans strains harbored a TOL plasmid with both pWW0- and pDK1-type xylE gene. P. oryzihabitans 29 had received the archetypal TOL plasmid pWW0 from Pseudomonas putida PaW85. As an application for environmental biotechnology, the biodegradation potential of oil-polluted soil and the success of bioremediation could be estimated by monitoring changes not only in the type and amount but also in transfer of degradation plasmids.
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rhizosphere effect of Galega orientalis in oil contaminated soil
Soil Biology & Biochemistry, 2006Co-Authors: Anna H Kaksonen, Minna M. Jussila, Kristina Lindstrom, Leena SuominenAbstract:Abstract Randomized lysimeters in an oil-contaminated field contained the following treatments: (1) Galega orientalis seeds inoculated with Rhizobium Galegae HAMBI 540, (2) bioaugmentation with Pseudomonas putida PaW85, and (3) R. Galegae -inoculated G. orientalis seeds plus bioaugmentation with P. putida PaW85. The bacterial abundance and diversity were analysed in composite samples after one growing season. A total of 208 m-toluate tolerating bacteria were isolated and screened with m-toluate tolerance and utilization tests, and the catechol test. Seventy-nine isolates were characterized with (GTG)5-PCR genomic fingerprinting and 16S rRNA gene PCR-RFLP ribotyping. Only 10% of the isolated strains were able to degrade m-toluate. Most of the m-toluate utilizing bacteria were catechol positive indicating the existence of a TOL plasmid. Rhizosphere effect of G. orientalis was manifested in oil-contaminated soil. G. orientalis and Pseudomonas bioaugmentation increased the amount of bacteria in oil-contaminated soil. G. orientalis especially together with Pseudomonas bioaugmentation increased the numbers of m-toluate utilizing and catechol positive bacteria in the soil samples indicating an increase in degradation potential. The rhizosphere of G. orientalis increased also the diversity of bacteria. More ribotypes were found in soils treated with G. orientalis and P. putida PaW85 compared to the untreated soil, but the diversity of the m-toluate utilizing bacteria did not significantly increase.
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potential of the Galega rhizobium Galegae system for bioremediation of oil contaminated soil
Food Technology and Biotechnology, 2003Co-Authors: Kristina Lindstrom, Jyrki Pitkajarvi, Minna M. Jussila, Katri Mäkeläinen, Hannamari Hintsa, Anna H Kaksonen, Lenna Mokelke, Leena SuominenAbstract:Summary Bioremediation potential of the nitrogen-fixing leguminous plant Galega orientalis Lam. and its microsymbiont Rhizobium Galegae was evaluated in microcosm and mesocosm scale in oil and BTEX (benzene, toluene, ethylbenzene, xylene) contaminated soils, with m-toluate serving as a model for the latter group. G. orientalis and Rhizobium Galegae remained viable in m-toluate fractions up to 3000 ppm. Plant growth and nodulation were inhibited in 500 ppm m-toluate, but were restored when plants were transferred to clean medium. In soil, G. orientalis nodulated and showed good growth in 2000 ppm m-toluate as well as in diesel-contaminated soil in the field, where the plant was stimulating bacterial growth in the rhizosphere. A collection of 52 indigenous m-toluate-tolerating bacteria isolated from oil-contaminated rhizosphere of G. orientalis was characterised and identified by classical and molecular biological methods. 16SrDNA PCR-RFLP and (GTG)5-PCR genomic fingerprinting combined with partial sequencing indicated the presence of five major lineages of the Bacteria domain. A TOL plasmid-specific xylE-PCR was developed in order to detect both active and potential degraders of m-toluate. The ability to degrade m-toluate in the presence of the gene xylE was detected only within the genus Pseudomonas. The isolates were tested for capacity to grow on m-toluate as their sole carbon and energy source. In laboratory experiments, the best rhizosphere isolates performed equally well to the positive control strain and are good candidates for inoculant production in the future. They have been tagged with marker genes for further studies on colonisation and persistence.
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evaluation of the Galega rhizobium Galegae system for the bioremediation of oil contaminated soil
Environmental Pollution, 2000Co-Authors: Leena Suominen, Minna M. Jussila, Katri Mäkeläinen, Martin Romantschuk, Kristina LindstromAbstract:The bioremediation potential of a nitrogen-fixing leguminous plant, Galega orientalis, and its microsymbiont Rhizobium Galegae was evaluated in BTX (benzene, toluene, xylene)-contaminated soils in microcosm and mesocosm scale. To measure the intrinsic tolerance of the organisms to m-toluate, a model compound representing BTX, G. orientalis and R. Galegae were cultivated under increasing concentrations of m-toluate alone and in association with Pseudomonas putida pWWO, a bacterial strain able to degrade toluene-derived compounds. The test plants and rhizobia remained viable in m-toluate concentrations as high as 3000 ppm. Plant growth was inhibited in concentrations higher than 500 ppm, but restituted when plants were transferred into m-toluate-free medium. Nodulation was blocked under the influence of m-toluate, but was restored after the plants were transferred into the non-contaminated media. In the mesocosm assay the Galega plants showed good growth, nodulation and nitrogen fixation, and developed a strong rhizosphere in soils contaminated with oil or spiked with 2000 ppm m-toluate. Thus, this legume system has good potential for use on oil-contaminated sites
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Evaluation of the Galega–Rhizobium Galegae system for the bioremediation of oil-contaminated soil
Environmental pollution (Barking Essex : 1987), 2000Co-Authors: Leena Suominen, Minna M. Jussila, Katri Mäkeläinen, Martin Romantschuk, Kristina LindstromAbstract:The bioremediation potential of a nitrogen-fixing leguminous plant, Galega orientalis, and its microsymbiont Rhizobium Galegae was evaluated in BTX (benzene, toluene, xylene)-contaminated soils in microcosm and mesocosm scale. To measure the intrinsic tolerance of the organisms to m-toluate, a model compound representing BTX, G. orientalis and R. Galegae were cultivated under increasing concentrations of m-toluate alone and in association with Pseudomonas putida pWWO, a bacterial strain able to degrade toluene-derived compounds. The test plants and rhizobia remained viable in m-toluate concentrations as high as 3000 ppm. Plant growth was inhibited in concentrations higher than 500 ppm, but restituted when plants were transferred into m-toluate-free medium. Nodulation was blocked under the influence of m-toluate, but was restored after the plants were transferred into the non-contaminated media. In the mesocosm assay the Galega plants showed good growth, nodulation and nitrogen fixation, and developed a strong rhizosphere in soils contaminated with oil or spiked with 2000 ppm m-toluate. Thus, this legume system has good potential for use on oil-contaminated sites
