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Extremophile Metal Resistance: Plasmid-Encoded Functions in Streptomyces mirabilis. Appl Environ Microbiol 2022; 88:e0008522. [PMID: 35604229 PMCID: PMC9195940 DOI: 10.1128/aem.00085-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The extreme metal tolerance of up to 130 mM NiSO4 in Streptomyces mirabilis P16B-1 was investigated. Genome sequencing revealed the presence of a large linear plasmid, pI. To identify plasmid-encoded determinants of metal resistance, a newly established transformation system was used to characterize the predicted plasmid-encoded loci nreB, hoxN, and copYZ. Reintroduction into the plasmid-cured S. mirabilis ΔpI confirmed that the predicted metal transporter gene nreB constitutes a nickel resistance factor, which was further supported by its heterologous expression in Escherichia coli. In contrast, the predicted nickel exporter gene hoxN decreased nickel tolerance, while copper tolerance was enhanced. The predicted copper-dependent transcriptional regulator gene copY did not induce tolerance toward either metal. Since genes for transfer were identified on the plasmid, its conjugational transfer to the metal-sensitive Streptomyces lividans TK24 was checked. This resulted in acquired tolerance toward 30 mM nickel and additionally increased the tolerance toward copper and cobalt, while oxidative stress tolerance remained unchanged. Intracellular nickel concentrations decreased in the transconjugant strain. The high extracellular nickel concentrations allowed for biomineralization. Plasmid transfer could also be confirmed into the co-occurring actinomycete Kribbella spp. in soil microcosms. IMPORTANCE Living in extremely metal-rich environments requires specific adaptations, and often, specific metal tolerance genes are encoded on a transferable plasmid. Here, Streptomyces mirabilis P16B-1, isolated from a former mining area and able to grow with up to 130 mM NiSO4, was investigated. The bacterial chromosome, as well as a giant plasmid, was sequenced. The plasmid-borne gene nreB was confirmed to confer metal resistance. A newly established transformation system allowed us to construct a plasmid-cured S. mirabilis as well as an nreB-rescued strain in addition to confirming nreB encoding nickel resistance if heterologously expressed in E. coli. The potential of intra- and interspecific plasmid transfer, together with the presence of metal resistance factors on that plasmid, underlines the importance of plasmids for transfer of resistance factors within a bacterial soil community.
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Fashola MO, Ngole-Jeme VM, Babalola OO. Heavy Metal Pollution from Gold Mines: Environmental Effects and Bacterial Strategies for Resistance. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2016; 13:ijerph13111047. [PMID: 27792205 PMCID: PMC5129257 DOI: 10.3390/ijerph13111047] [Citation(s) in RCA: 233] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 10/12/2016] [Accepted: 10/14/2016] [Indexed: 12/20/2022]
Abstract
Mining activities can lead to the generation of large quantities of heavy metal laden wastes which are released in an uncontrolled manner, causing widespread contamination of the ecosystem. Though some heavy metals classified as essential are important for normal life physiological processes, higher concentrations above stipulated levels have deleterious effects on human health and biota. Bacteria able to withstand high concentrations of these heavy metals are found in the environment as a result of various inherent biochemical, physiological, and/or genetic mechanisms. These mechanisms can serve as potential tools for bioremediation of heavy metal polluted sites. This review focuses on the effects of heavy metal wastes generated from gold mining activities on the environment and the various mechanisms used by bacteria to counteract the effect of these heavy metals in their immediate environment.
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Affiliation(s)
- Muibat Omotola Fashola
- Food Security and Safety Niche Area, Faculty of Agriculture, Science and Technology, North-West University, Private Bag X2046, Mmabatho 2735, South Africa.
| | - Veronica Mpode Ngole-Jeme
- Department of Environmental Sciences, College of Agriculture and Environmental Sciences, UNISA, Florida, Private Bag X6 Florida, Roodepoort 1710, South Africa.
| | - Olubukola Oluranti Babalola
- Food Security and Safety Niche Area, Faculty of Agriculture, Science and Technology, North-West University, Private Bag X2046, Mmabatho 2735, South Africa.
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Fierros-Romero G, Gómez-Ramírez M, Arenas-Isaac GE, Pless RC, Rojas-Avelizapa NG. Identification of Bacillus megaterium and Microbacterium liquefaciens genes involved in metal resistance and metal removal. Can J Microbiol 2016; 62:505-13. [PMID: 27210016 DOI: 10.1139/cjm-2015-0507] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bacillus megaterium MNSH1-9K-1 and Microbacterium liquefaciens MNSH2-PHGII-2, 2 nickel- and vanadium-resistant bacteria from mine tailings located in Guanajuato, Mexico, are shown to have the ability to remove 33.1% and 17.8% of Ni, respectively, and 50.8% and 14.0% of V, respectively, from spent petrochemical catalysts containing 428 ± 30 mg·kg(-1) Ni and 2165 ± 77 mg·kg(-1) V. In these strains, several Ni resistance determinants were detected by conventional PCR. The nccA (nickel-cobalt-cadmium resistance) was found for the first time in B. megaterium. In M. liquefaciens, the above gene as well as the czcD gene (cobalt-zinc-cadmium resistance) and a high-affinity nickel transporter were detected for the first time. This study characterizes the resistance of M. liquefaciens and B. megaterium to Ni through the expression of genes conferring metal resistance.
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Affiliation(s)
- Grisel Fierros-Romero
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico.,Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico
| | - Marlenne Gómez-Ramírez
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico.,Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico
| | - Ginesa E Arenas-Isaac
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico.,Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico
| | - Reynaldo C Pless
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico.,Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico
| | - Norma G Rojas-Avelizapa
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico.,Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del IPN, Cerro Blanco 141, Col. Colinas del Cimatario, Querétaro, Querétaro 76090, Mexico
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Monsieurs P, Hobman J, Vandenbussche G, Mergeay M, Van Houdt R. Response of Cupriavidus metallidurans CH34 to Metals. ACTA ACUST UNITED AC 2015. [DOI: 10.1007/978-3-319-20594-6_3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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5
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MiniUIB, a novel minitransposon-based system for stable insertion of foreign DNA into the genomes of Gram-negative and Gram-positive bacteria. Appl Environ Microbiol 2013; 79:1629-38. [PMID: 23275505 DOI: 10.1128/aem.03214-12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Transposition of the insertion sequence (IS) ISPpu12 is actively induced after conjugative interaction. The transposase of this IS can act in trans on structures flanked by inverted repeats similar to those of the transposon. Based on that fact, an ISPpu12-based minitransposon, miniUIB, has been constructed in order to biotechnologically exploit the self-regulation of ISPpu12 and its increased activity after conjugative interaction. Mobilization of the miniUIB structure into the genome of Pseudomonas stutzeri AN10 after conjugative interaction was demonstrated. A single gene, i.e., the kanamycin resistance determinant, or large genetic structures of >12 kb, i.e., alkBFGHJKL and alkST operons of Pseudomonas putida TF4-1L (GPo1), have been easily integrated in P. stutzeri AN10 by an RP4-based delivery system. Therefore, the integration of the alk determinants by use of the miniUIB system has extended the biodegradation capabilities of this strain. Plasmid pJOC100, containing the transposase and regulator genes of ISPpu12 adjacent to the miniUIB structure, was constructed in order to extend the host range of this biotechnologically useful genetic tool to other model and real-world bacteria. The effectiveness of the system for random mutagenesis in a phylogenetic wide range of bacteria and for the insertion of novel functions has been demonstrated, even in successive steps.
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Weyens N, Truyens S, Saenen E, Boulet J, Dupae J, Taghavi S, van der Lelie D, Carleer R, Vangronsveld J. Endophytes and their potential to deal with co-contamination of organic contaminants (toluene) and toxic metals (nickel) during phytoremediation. INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 2011; 13:244-255. [PMID: 21598790 DOI: 10.1080/15226511003753920] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The aim was to investigate if engineered endophytes that are capable of degrading organic contaminants, and deal with or ideally improve uptake and translocation of toxic metals, can improve phytoremediation of mixed organic-metal pollution. As a model system, yellow lupine was inoculated with the endophyte Burkholderia cepacia VM1468 possessing (a) the pTOM-Bu61 plasmid, coding for constitutive toluene/TCE degradation, and (b) the chromosomally inserted ncc-nre Ni resistance/sequestration system. As controls, plants were inoculated with B. vietnamiensis BU61 (pTOM-Bu61) and B. cepacia BU72 (containing the ncc-nre Ni resistance/sequestration system). Plants were exposed to mixes of toluene and Ni. Only inoculation with B. cepacia VM1468 resulted in decreased Ni and toluene phytotoxicity, as measured by a protective effect on plant growth and decreased activities of enzymes involved in antioxidative defence (catalase, guaiacol peroxidase, superoxide dismutase) in the roots. Besides, plants inoculated with B. cepacia VM1468 and B. vietnamiensis BU61 released less toluene through the leaves than non-inoculated plants and those inoculated with B. cepacia BU72. Ni-uptake in roots was slightly increased for B. cepacia BU72 inoculated plants. These results indicate that engineered endophytes have the potential to assist their host plant to deal with co-contamination of toxic metals and organic contaminants during phytoremediation.
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Affiliation(s)
- Nele Weyens
- Hasselt University, Centre for Environmental Sciences, Diepenbeek, Belgium
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Genome survey and characterization of endophytic bacteria exhibiting a beneficial effect on growth and development of poplar trees. Appl Environ Microbiol 2008; 75:748-57. [PMID: 19060168 DOI: 10.1128/aem.02239-08] [Citation(s) in RCA: 273] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The association of endophytic bacteria with their plant hosts has a beneficial effect for many different plant species. Our goal is to identify endophytic bacteria that improve the biomass production and the carbon sequestration potential of poplar trees (Populus spp.) when grown in marginal soil and to gain an insight in the mechanisms underlying plant growth promotion. Members of the Gammaproteobacteria dominated a collection of 78 bacterial endophytes isolated from poplar and willow trees. As representatives for the dominant genera of endophytic gammaproteobacteria, we selected Enterobacter sp. strain 638, Stenotrophomonas maltophilia R551-3, Pseudomonas putida W619, and Serratia proteamaculans 568 for genome sequencing and analysis of their plant growth-promoting effects, including root development. Derivatives of these endophytes, labeled with gfp, were also used to study the colonization of their poplar hosts. In greenhouse studies, poplar cuttings (Populus deltoides x Populus nigra DN-34) inoculated with Enterobacter sp. strain 638 repeatedly showed the highest increase in biomass production compared to cuttings of noninoculated control plants. Sequence data combined with the analysis of their metabolic properties resulted in the identification of many putative mechanisms, including carbon source utilization, that help these endophytes to thrive within a plant environment and to potentially affect the growth and development of their plant hosts. Understanding the interactions between endophytic bacteria and their host plants should ultimately result in the design of strategies for improved poplar biomass production on marginal soils as a feedstock for biofuels.
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Moreels D, Crosson G, Garafola C, Monteleone D, Taghavi S, Fitts JP, van der Lelie D. Microbial community dynamics in uranium contaminated subsurface sediments under biostimulated conditions with high nitrate and nickel pressure. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2008; 15:481-491. [PMID: 18712423 DOI: 10.1007/s11356-008-0034-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Accepted: 08/06/2008] [Indexed: 05/26/2023]
Abstract
BACKGROUND, AIM, AND SCOPE The subsurface at the Oak Ridge Field Research Center represents an extreme and diverse geochemical environment that places different stresses on the endogenous microbial communities, including low pH, elevated nitrate concentrations, and the occurrence of heavy metals and radionuclides, including hexavalent uranium [U(VI)]. The in situ immobilization of U(VI) in the aquifer can be achieved through microbial reduction to relatively insoluble U(IV). However, a high redox potential due to the presence of nitrate and the toxicity of heavy metals will impede this process. Our aim is to test biostimulation of the endogenous microbial communities to improve nitrate reduction and subsequent U(VI) reduction under conditions of elevated heavy metals. MATERIALS AND METHODS Column experiments were used to test the possibility of using biostimulation via the addition of ethanol as a carbon source to improve nitrate reduction in the presence of elevated aqueous nickel. We subsequently analyzed the composition of the microbial communities that became established and their potential for U(VI) reduction and its in situ immobilization. RESULTS Phylogenetic analysis revealed that the microbial population changed from heavy metal sensitive members of the actinobacteria, alpha- and gamma-proteobacteria to a community dominated by heavy metal resistant (nickel, cadmium, zinc, and cobalt resistant), nitrate reducing beta- and gamma-proteobacteria, and sulfate reducing Clostridiaceae. Coincidentally, synchrotron X-ray absorption spectroscopy analyses indicated that the resulting redox conditions favored U(VI) reduction transformation to insoluble U(IV) species associated with soil minerals and biomass. DISCUSSION This study shows that the necessary genetic information to adapt to the implemented nickel stress resides in the endogenous microbial population present at the Oak Ridge FRC site, which changed from a community generally found under oligotrophic conditions to a community able to withstand the stress imposed by heavy metals, while efficiently reducing nitrate as electron donor. Once nitrate was reduced efficient reduction and in situ immobilization of uranium was observed. CONCLUSIONS This study provides evidence that stimulating the metabolism of the endogenous bacterial population at the Oak Ridge FRC site by adding ethanol, a suitable carbon source, results in efficient nitrate reduction under conditions of elevated nickel, and a decrease of the redox potential such that sulfate and iron reducing bacteria are able to thrive and create conditions favorable for the reduction and in situ immobilization of uranium. Since we have found that the remediation potential resides within the endogenous microbial community, we believe it will be feasible to conduct field tests. RECOMMENDATIONS AND PERSPECTIVES Biostimulation of endogenous bacteria provides an efficient tool for the successful in situ remediation of mixed-waste sites, particularly those co-contaminated with heavy metals, nitrate and radionuclides, as found in the United States and other countries as environmental legacies of the nuclear age.
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Affiliation(s)
- David Moreels
- Biology Department, Brookhaven National Laboratory, Bldg. 463, Upton, NY 11973, USA
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Haferburg G, Kloess G, Schmitz W, Kothe E. "Ni-struvite" - a new biomineral formed by a nickel resistant Streptomyces acidiscabies. CHEMOSPHERE 2008; 72:517-523. [PMID: 18410951 DOI: 10.1016/j.chemosphere.2008.02.050] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Revised: 02/20/2008] [Accepted: 02/22/2008] [Indexed: 05/26/2023]
Abstract
Biomineralization dependent on bacterial activity has been described for struvite which is formed in soils, guano, putrescent matter and sediments. A new biomineral containing nickel instead of magnesium, Ni(NH4)(PO4) . 6H2O, has been identified. It was formed by nickel resistant Streptomyces acidiscabies E13, and putatively named nickel struvite. The mineral formation is dependent on biological activity since non-viable bacterial cells are not capable to induce formation of Ni-struvite under identical conditions. Formation of Ni-struvite was observed on colony surfaces upon prolonged incubation of solid minimal or complex media containing elevated concentrations of 8-15mM NiCl2. The formation of magnesium containing crystals was not observed although Mg2+ is present in the medium. However, the process was not depending on desiccation since small crystals attached to the mycelial biomass of the bacteria were observed microscopically also in liquid cultures of nickel supplemented minimal and complex media after two weeks of incubation. The capacity to induce biomineralization of a nickel containing mineral is postulated to constitute a resistance factor, allowing the soil bacterium to withstand high nickel concentrations. The strain shows nickel resistance as an adaption to its habitat, since this bacterium was isolated from a former uranium mining site in Eastern Thuringia, Germany, where nickel concentrations of up to 2000ppm (translating to appr. 30mM) occur as a result of former mining activities.
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Affiliation(s)
- Götz Haferburg
- Institute of Microbiology, Friedrich-Schiller-University, Neugasse 25, 07743 Jena, Germany.
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Nickel resistance determinants in bradyrhizobium strains from nodules of the endemic New Caledonia legume Serianthes calycina. Appl Environ Microbiol 2007; 73:8018-22. [PMID: 17951443 DOI: 10.1128/aem.01431-07] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bradyrhizobium strains, isolated in New Caledonia from nodules of the endemic legume Serianthes calycina growing in nickel-rich soils, were able to grow in the presence of 15 mM NiCl2. The genomes of these strains harbored two Ni resistance determinants, the cnr and nre operons. By constructing a cnrA mutant, we demonstrated that the cnr operon determines the high nickel resistance in Bradyrhizobium strains.
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Van Nostrand JD, Khijniak TV, Gentry TJ, Novak MT, Sowder AG, Zhou JZ, Bertsch PM, Morris PJ. Isolation and characterization of four gram-positive nickel-tolerant microorganisms from contaminated sediments. MICROBIAL ECOLOGY 2007; 53:670-82. [PMID: 17404787 DOI: 10.1007/s00248-006-9160-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Revised: 08/14/2006] [Accepted: 08/30/2006] [Indexed: 05/14/2023]
Abstract
Microbial communities from riparian sediments contaminated with high levels of Ni and U were examined for metal-tolerant microorganisms. Isolation of four aerobic Ni-tolerant, Gram-positive heterotrophic bacteria indicated selection pressure from Ni. These isolates were identified as Arthrobacter oxydans NR-1, Streptomyces galbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatospora cystarginea NR-4 based on partial 16S rDNA sequences. A functional gene microarray containing gene probes for functions associated with biogeochemical cycling, metal homeostasis, and organic contaminant degradation showed little overlap among the four isolates. Fifteen of the genes were detected in all four isolates with only two of these related to metal resistance, specifically to tellurium. Each of the four isolates also displayed resistance to at least one of six antibiotics tested, with resistance to kanamycin, gentamycin, and ciprofloxacin observed in at least two of the isolates. Further characterization of S. aureofaciens NR-3 and K. cystarginea NR-4 demonstrated that both isolates expressed Ni tolerance constitutively. In addition, both were able to grow in higher concentrations of Ni at pH 6 as compared with pH 7 (42.6 and 8.5 mM Ni at pH 6 and 7, respectively). Tolerance to Cd, Co, and Zn was also examined in these two isolates; a similar pH-dependent metal tolerance was observed when grown with Co and Zn. Neither isolate was tolerant to Cd. These findings suggest that Ni is exerting a selection pressure at this site for metal-resistant actinomycetes.
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Affiliation(s)
- Joy D Van Nostrand
- Marine Biomedicine and Environmental Science Center, Medical University of South Carolina, Charleston, SC 29412, USA
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Lee YK, Chang HH, Lee HJ, Park H, Lee KH, Joe MH. Isolation of a novel plasmid, pNi15, from Enterobacter sp. Ni15 containing a nickel resistance gene. FEMS Microbiol Lett 2006; 257:177-81. [PMID: 16553850 DOI: 10.1111/j.1574-6968.2006.00130.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
We isolated nickel-resistant bacterium from soil in order to identify a novel nickel resistance determinant. Using 16S rRNA gene sequencing, an isolate was identified as Enterobacter sp. Ni15. This species showed a medium-level (resistant to up to 10 mM) nickel resistance in nutrient-rich media. Enterobacter sp. Ni15 has a novel plasmid, pNi15, and an increased nickel resistance to Escherichia coli DH5alphain trans. To isolate the nickel resistance gene from pNi15, the plasmid was digested with XbaI and its fragments were cloned into pBluescriptIISK(+). The clones were transferred into E. coli DH5alpha. The nickel resistance of the clones was then assayed. From these results, a pNi15100 isolate containing a 5,328 bp XbaI fragment of pNi15 was identified and sequenced. The E. coli DH5alpha harboring the pNi15100 showed a resistance to up to 7 mM nickel. Using a subcloning analysis, we were able to identify the novel nickel resistance determinant: the nrp gene encoding the putative proteins NrpA and NrpB.
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Affiliation(s)
- Young-Keun Lee
- Radiation Application Research Division, ARTI, Korea Atomic Energy Research Institute, Sinjeong-Dong, Jeongeup, Korea.
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Taghavi S, Barac T, Greenberg B, Borremans B, Vangronsveld J, van der Lelie D. Horizontal gene transfer to endogenous endophytic bacteria from poplar improves phytoremediation of toluene. Appl Environ Microbiol 2005; 71:8500-5. [PMID: 16332840 PMCID: PMC1317371 DOI: 10.1128/aem.71.12.8500-8505.2005] [Citation(s) in RCA: 269] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Accepted: 09/09/2005] [Indexed: 11/20/2022] Open
Abstract
Poplar, a plant species frequently used for phytoremediation of groundwater contaminated with organic solvents, was inoculated with the endophyte Burkholderia cepacia VM1468. This strain, whose natural host is yellow lupine, contains the pTOM-Bu61 plasmid coding for constitutively expressed toluene degradation. Noninoculated plants or plants inoculated with the soil bacterium B. cepacia Bu61(pTOM-Bu61) were used as controls. Inoculation of poplar had a positive effect on plant growth in the presence of toluene and reduced the amount of toluene released via evapotranspiration. These effects were more dramatic for VM1468, the endophytic strain, than for Bu61. Remarkably, none of the strains became established at detectable levels in the endophytic community, but there was horizontal gene transfer of pTOM-Bu61 to different members of the endogenous endophytic community, both in the presence and in the absence of toluene. This work is the first report of in planta horizontal gene transfer among plant-associated endophytic bacteria and demonstrates that such transfer could be used to change natural endophytic microbial communities in order to improve the remediation of environmental insults.
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Affiliation(s)
- Safiyh Taghavi
- Brookhaven National Laboratory, Biology Department, Building 463, Upton, NY 11973-5000.
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Barac T, Taghavi S, Borremans B, Provoost A, Oeyen L, Colpaert JV, Vangronsveld J, van der Lelie D. Engineered endophytic bacteria improve phytoremediation of water-soluble, volatile, organic pollutants. Nat Biotechnol 2004; 22:583-8. [PMID: 15077119 DOI: 10.1038/nbt960] [Citation(s) in RCA: 269] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2004] [Accepted: 02/19/2004] [Indexed: 11/08/2022]
Abstract
Phytoremediation of highly water soluble and volatile organic xenobiotics is often inefficient because plants do not completely degrade these compounds through their rhizospheres. This results in phytotoxicity and/or volatilization of chemicals through the leaves, which can cause additional environmental problems. We demonstrate that endophytic bacteria equipped with the appropriate degradation pathway improve the in planta degradation of toluene. We introduced the pTOM toluene-degradation plasmid of Burkholderia cepacia G4 into B. cepacia L.S.2.4, a natural endophyte of yellow lupine. After surface-sterilized lupine seeds were successfully inoculated with the recombinant strain, the engineered endophytic bacteria strongly degraded toluene, resulting in a marked decrease in its phytotoxicity, and a 50-70% reduction of its evapotranspiration through the leaves. This strategy promises to improve the efficiency of phytoremediating volatile organic contaminants.
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Affiliation(s)
- Tanja Barac
- Limburgs Universitair Centrum (LUC), Department of Environmental Biology, Universitaire Campus building D, B-3590 Diepenbeek, Belgium
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Abstract
The prospect of the deliberate environmental release of genetically manipulated microorganisms has given rise to a great deal of polemic. Amongst the rational scientific concerns are those concerned with the fate of the released bacteria, the fate of the recombinant genes that they carry, the selective pressures acting upon them in different environmental situations and the long term effects on the environment and human health. All recombinant DNA is carried by vectors (plasmids, transposons or bacteriophage or remnants of these). Thus the way in which recombinant constructions are made may itself lead to potential biosafety concerns, irrespective of the host bacterium and the recombinant DNA fragment of primary interest. The purpose of the present review is to assess progress in improved vector design aimed at eliminating risks due to the way recombinant vectors are constructed. Improved vector constructions include the avoidance of the use, or removal, of antibiotic resistance genes, the use of defective transposons rather than plasmids in order to reduce horizontal transfer and the development of conditionally lethal suicide systems. More recently, new site-specific recombination systems have permitted transposon vectors to be manipulated following strain construction, but before environmental release, so that virtually all recombinant DNA not directly involved in the release experiment is eliminated. Such bacteria are thus pseudo-wild type in that they contain no heterologous DNA other than the genes of interest.
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Affiliation(s)
- John Davison
- Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique, INRA-Versailles, 78026 Versailles Cedex, France.
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