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Macedo G, Olesen AK, Maccario L, Hernandez Leal L, v. d. Maas P, Heederik D, Mevius D, Sørensen SJ, Schmitt H. Horizontal Gene Transfer of an IncP1 Plasmid to Soil Bacterial Community Introduced by Escherichia coli through Manure Amendment in Soil Microcosms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:11398-11408. [PMID: 35896060 PMCID: PMC9387108 DOI: 10.1021/acs.est.2c02686] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The quantification and identification of new plasmid-acquiring bacteria in representative mating conditions is critical to characterize the risk of horizontal gene transfer in the environment. This study aimed to quantify conjugation events resulting from manure application to soils and identify the transconjugants resulting from these events. Conjugation was quantified at multiple time points by plating and flow cytometry, and the transconjugants were recovered by fluorescence-activated cell sorting and identified by 16S rRNA sequencing. Overall, transconjugants were only observed within the first 4 days after manure application and at values close to the detection limits of this experimental system (1.00-2.49 log CFU/g of manured soil, ranging between 10-5 and 10-4 transconjugants-to-donor ratios). In the pool of recovered transconjugants, we found amplicon sequence variants (ASVs) of genera whose origin was traced to soils (Bacillus and Nocardioides) and manure (Comamonas and Rahnella). This work showed that gene transfer from fecal to soil bacteria occurred despite the less-than-optimal conditions faced by manure bacteria when transferred to soils, but these events were rare, mainly happened shortly after manure application, and the plasmid did not colonize the soil community. This study provides important information to determine the risks of AMR spread via manure application.
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Affiliation(s)
- Gonçalo Macedo
- Department
of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
- Wetsus,
European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
| | - Asmus K. Olesen
- Department
of Biology, University of Copenhagen, Copenhagen 2100, Denmark
| | - Lorrie Maccario
- Department
of Biology, University of Copenhagen, Copenhagen 2100, Denmark
| | - Lucia Hernandez Leal
- Wetsus,
European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
| | - Peter v. d. Maas
- Van
Hall Larenstein, University of Applied Sciences, Agora 1, 8901 BV Leeuwarden, The Netherlands
| | - Dick Heederik
- Institute
for Risk Assessment Sciences, Utrecht University, Yalelaan 2, 3584 CM Utrecht, The Netherlands
| | - Dik Mevius
- Department
of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
- Department
of Bacteriology and Epidemiology, Wageningen
Bioveterinary Research, Houtribweg 39, 8221 RA Lelystad, The Netherlands
| | - Søren J. Sørensen
- Department
of Biology, University of Copenhagen, Copenhagen 2100, Denmark
| | - Heike Schmitt
- Wetsus,
European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands
- Institute
for Risk Assessment Sciences, Utrecht University, Yalelaan 2, 3584 CM Utrecht, The Netherlands
- Centre
for Infectious Disease Control, National
Institute for Public Health and the Environment (RIVM), Antonie van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands
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2
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Musovic S, Klümper U, Dechesne A, Magid J, Smets BF. Long-term manure exposure increases soil bacterial community potential for plasmid uptake. ENVIRONMENTAL MICROBIOLOGY REPORTS 2014; 6:125-30. [PMID: 24596284 DOI: 10.1111/1758-2229.12138] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 10/21/2013] [Accepted: 11/05/2013] [Indexed: 05/26/2023]
Abstract
Microbial communities derived from soils subject to different agronomic treatments were challenged with three broad host range plasmids, RP4, pIPO2tet and pRO101, via solid surface filter matings to assess their permissiveness. Approximately 1 in 10 000 soil bacterial cells could receive and maintain the plasmids. The community permissiveness increased up to 100% in communities derived from manured soil. While the plasmid transfer frequency was significantly influenced by both the type of plasmid and the agronomic treatment, the diversity of the transconjugal pools was purely plasmid dependent and was dominated by β- and γ-Proteobacteria.
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Affiliation(s)
- Sanin Musovic
- Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark
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3
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Ikuma K, Holzem RM, Gunsch CK. Impacts of organic carbon availability and recipient bacteria characteristics on the potential for TOL plasmid genetic bioaugmentation in soil slurries. CHEMOSPHERE 2012; 89:158-163. [PMID: 22743182 DOI: 10.1016/j.chemosphere.2012.05.086] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 05/23/2012] [Accepted: 05/25/2012] [Indexed: 06/01/2023]
Abstract
The effectiveness of genetic bioaugmentation relies on efficient plasmid transfer between donor and recipient cells as well as the plasmid's phenotype in the recipient cell. In the present study, the effects of varying organic carbon substrates, initial recipient-to-donor cell density ratios, and mixtures of known recipient bacterial strains on the conjugation and function of a TOL plasmid were tested in sterile soil slurry batch reactors. The presence of soil organic carbon was sufficient in ensuring TOL plasmid transconjugant occurrence (up to 2.1±0.5%) for most recipient strains in soil slurry batch mating experiments. The addition of glucose had limited effects on transconjugant occurrence; however, glucose amendment increased the specific toluene degradation rates of some Enterobacteriaceae transconjugants in soil slurry. Initial cell density ratios and mixtures of recipient strains had smaller impacts on plasmid conjugation and resulting phenotype functionality. These observations suggest that genetic bioaugmentation may be improved by minimal altering of environmental conditions.
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Affiliation(s)
- Kaoru Ikuma
- Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708, USA
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4
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Drudge CN, Warren LA. Prokaryotic Horizontal Gene Transfer in Freshwater Lakes: Implications of Dynamic Biogeochemical Zonation. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/jep.2012.312181] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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5
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Merkey BV, Lardon LA, Seoane JM, Kreft JU, Smets BF. Growth dependence of conjugation explains limited plasmid invasion in biofilms: an individual-based modelling study. Environ Microbiol 2011; 13:2435-52. [DOI: 10.1111/j.1462-2920.2011.02535.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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6
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Occurrence and persistence of indigenous transconjugants carrying conjugative plasmids in soil. J Biosci Bioeng 2009; 108:231-4. [DOI: 10.1016/j.jbiosc.2009.03.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Revised: 03/22/2009] [Accepted: 03/23/2009] [Indexed: 11/22/2022]
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7
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Smets BF, Lardon L. Mass action models describing extant horizontal transfer of plasmids: inferences and parameter sensitivities. Methods Mol Biol 2009; 532:289-305. [PMID: 19271192 DOI: 10.1007/978-1-60327-853-9_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Predicting the fate of horizontally transmissible elements in extant microbial communities might be facilitated by the availability of suitable mathematical models. Since the mid-1970s, mass action models have been introduced to describe the transfer of conjugal and mobilizable genetic elements. This chapter will summarize and explain the assumptions behind spatially homogenous models, and show the predictions by these models under typical scenarios, such as evaluating existence conditions of conjugal plasmids under chemostat or seasonal growth conditions. Special attention is given to the sensitivity of the outcomes to the various plasmid dynamic parameters. For our analysis, we developed a set of user-friendly MatLab routines, which are deposited in the public domain. We hope that the availability of these routines will encourage the computationally untrained microbiologist to make use of these mathematical models. Finally, further permutations, as well as limitations of these mass action models in view of the structured complexity of most microbial systems are addressed.
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Affiliation(s)
- Barth F Smets
- Microbial Ecology Research Group, Institute of Environment & Resources DTU, Technical University of Denmark, Lyngby, Denmark
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8
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Boon N, Depuydt S, Verstraete W. Evolutionary algorithms and flow cytometry to examine the parameters influencing transconjugant formation. FEMS Microbiol Ecol 2006; 55:17-27. [PMID: 16420611 DOI: 10.1111/j.1574-6941.2005.00002.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
An evolutionary algorithm was used to determine the optimal combination of parameters for transconjugant formation. As a model system, a gfp tagged TOL plasmid pWW0 was chosen to examine transfer from Pseudomonas putida to Escherichia coli. A comparison of flow cytometry results with plating and microscopy showed that the majority of transconjugants were not culturable. The transconjugant ratio therefore was determined by flow cytometry. The evolutionary algorithm showed that the optimal conditions were obtained at 28 degrees C and at the highest nutrient concentrations. This work demonstrates that evolutionary algorithms can be used to find optimal parameter interactions in environmental microbiology.
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Affiliation(s)
- Nico Boon
- Laboratory of Microbial Ecology and Technology, LabMET, Ghent University, Ghent, Belgium.
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9
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Sørensen SJ, Bailey M, Hansen LH, Kroer N, Wuertz S. Studying plasmid horizontal transfer in situ: a critical review. Nat Rev Microbiol 2005; 3:700-10. [PMID: 16138098 DOI: 10.1038/nrmicro1232] [Citation(s) in RCA: 445] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
This review deals with the prospective, experimental documentation of horizontal gene transfer (HGT) and its role in real-time, local adaptation. We have focused on plasmids and their function as an accessory and/or adaptive gene pool. Studies of the extent of HGT in natural environments have identified certain hot spots, and many of these involve biofilms. Biofilms are uniquely suited for HGT, as they sustain high bacterial density and metabolic activity, even in the harshest environments. Single-cell detection of donor, recipient and transconjugant bacteria in various natural environments, combined with individual-based mathematical models, has provided a new platform for HGT studies.
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Affiliation(s)
- Søren J Sørensen
- Department of Microbiology, Institute of Biology, University of Copenhagen, Sølvgade 83H, 1307 Copenhagen K, Denmark.
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Lambertsen LM, Molin S, Kroer N, Thomas CM. Transcriptional regulation of pWW0 transfer genes in Pseudomonas putida KT2440. Plasmid 2005; 52:169-81. [PMID: 15518874 DOI: 10.1016/j.plasmid.2004.06.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2004] [Revised: 06/01/2004] [Indexed: 11/26/2022]
Abstract
The conjugative IncP-9 plasmid pWW0 (TOL) carries transfer genes, many of whose functions can be predicted from sequence similarities to the well-studied IncW and IncP-1 plasmids, and that are clustered with the replication and maintenance genes of the plasmid core. In this study we show that the IncP-9 transfer genes are transcribed from at least three promoter regions. The promoters for traA and traD act divergently from the region found to encode the origin of transfer, oriT. These promoters regulate expression of traA, B, and perhaps traC in one direction and traD in the other, all of whose gene products are predicted to be involved in relaxasome formation and DNA processing during transfer, and they are repressed by TraA. The third promoter region, upstream of mpfR, is responsible for transcription of mpfR and mpfA to mpfJ, encoding proteins involved in mating pair formation. Transcription from this region is negatively autoregulated by MpfR. Thus the pWW0 transfer genes, like those of the IncP-1 plasmids, are expressed at all times, but kept in control by a negative feed back loop to limit the metabolic burden on the host. Although many of the related mating pair formation systems are, as in pWW0, transcribed divergently from an operon for replication and/or stable inheritance functions, MpfR is not related to the known regulatory proteins of these other transfer systems outside those of the IncP-9 family and indeed the regulators tend to be specific for each plasmid family. This suggests that the general pattern of genetic organisation exhibited by these systems has arisen a number of times independently and must therefore be highly favourable to plasmid survival and spread.
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Affiliation(s)
- Lotte M Lambertsen
- Molecular Microbial Ecology Group, Centre for Biomedical Microbiology, BioCentrum-DTU, Building 301, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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11
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Pinedo CA, Smets BF. Conjugal TOL transfer from Pseudomonas putida to Pseudomonas aeruginosa: effects of restriction proficiency, toxicant exposure, cell density ratios, and conjugation detection method on observed transfer efficiencies. Appl Environ Microbiol 2005; 71:51-7. [PMID: 15640169 PMCID: PMC544212 DOI: 10.1128/aem.71.1.51-57.2005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The effects of restriction proficiency and premating exposure to toxicants on conjugal transfer of the TOL plasmid between Pseudomonas spp. was investigated by examinations of filter matings. A Pseudomonas putida KT2442-derived strain carrying a gfp-tagged variant of the TOL plasmid was used as a donor, and both restriction-deficient (PAO1162N) and -proficient (PAO2002N) Pseudomonas aeruginosa strains were used as recipients. The in situ enumeration of conjugation events allowed us to obtain frequency estimates that were unbiased by transconjugant growth or plasmid retransfer. We observed a strong dependence of the plasmid transfer frequency on the initial donor-to-recipient ratio of surface matings, which invalidated the use of mass action-based plasmid transfer kinetic estimators. Careful control of the initial parental cell densities permitted evaluations of the true effects of restriction proficiency and toxicant exposure on TOL transfer. At standard donor-to-recipient ratios (10(-3) for PAO1162N and 2 x 10(1) for PAO2002N) and total cell densities (10(5) cells/mm(2) for PAO1162N and 10(6) cells/mm(2) for PAO2002N), plasmid transfer frequencies without toxicant exposure were approximately 10(-7) (events/mm(2))(-1) for PAO1162N and 10(-11) (events/mm(2))(-1) for PAO2002N based on in situ observations of conjugation events. The enumeration of transconjugants via selective plating yielded transfer frequencies that were up to 1 order of magnitude lower. Premating exposure to sodium dodecyl sulfate (1 to 10 mM) significantly increased the transfer frequency for the restriction-proficient strain PAO2002N (P < 0.05) but not for the restriction-deficient strain PAO1162N. On the other hand, premating exposure to ethanol, toluene, or phenol had no positive effect on the plasmid transfer frequency. Clearly, restriction proficiency provides a strong barrier to interspecific transfer of the TOL plasmid, and this barrier was only marginally attenuated by recipient exposure to toxicants within the ranges examined.
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Affiliation(s)
- Catalina Arango Pinedo
- Environmental Engineering Program, Department of Civil and Environmental Engineering, University of Connecticut, Storrs, Connecticut, USA
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12
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Coombs JM, Barkay T. Molecular evidence for the evolution of metal homeostasis genes by lateral gene transfer in bacteria from the deep terrestrial subsurface. Appl Environ Microbiol 2004; 70:1698-707. [PMID: 15006795 PMCID: PMC368364 DOI: 10.1128/aem.70.3.1698-1707.2004] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lateral gene transfer (LGT) plays a vital role in increasing the genetic diversity of microorganisms and promoting the spread of fitness-enhancing phenotypes throughout microbial communities. To date, LGT has been investigated in surface soils, natural waters, and biofilm communities but not in the deep terrestrial subsurface. Here we used a combination of molecular analyses to investigate the role of LGT in the evolution of metal homeostasis in lead-resistant subsurface bacteria. A nested PCR approach was employed to obtain DNA sequences encoding P(IB)-type ATPases, which are proteins that transport toxic or essential soft metals such as Zn(II), Cd(II), and Pb(II) through the cell wall. Phylogenetic incongruencies between a 16S rRNA gene tree and a tree based on 48 P(IB)-type ATPase amplicons and sequences available for complete bacterial genomes revealed an ancient transfer from a member of the beta subclass of the Proteobacteria (beta-proteobacterium) that may have predated the diversification of the genus Pseudomonas. Four additional phylogenetic incongruencies indicate that LGT has occurred among groups of beta- and gamma-proteobacteria. Two of these transfers appeared to be recent, as indicated by an unusual G+C content of the P(IB)-type ATPase amplicons. This finding provides evidence that LGT plays a distinct role in the evolution of metal homeostasis in deep subsurface bacteria, and it shows that molecular evolutionary approaches may be used for investigation of this process in microbial communities in specific environments.
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Affiliation(s)
- J M Coombs
- Department of Biochemistry and Microbiology, Cook College, Rutgers University, New Brunswick, New Jersey 08901, USA
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13
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Mølbak L, Licht TR, Kvist T, Kroer N, Andersen SR. Plasmid transfer from Pseudomonas putida to the indigenous bacteria on alfalfa sprouts: characterization, direct quantification, and in situ location of transconjugant cells. Appl Environ Microbiol 2003; 69:5536-42. [PMID: 12957943 PMCID: PMC194921 DOI: 10.1128/aem.69.9.5536-5542.2003] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The transfer of the plasmids pJKJ5 and TOL (pWWO) from Pseudomonas putida to the indigenous bacterial community on alfalfa sprouts was studied. Tagging with fluorescent protein markers allowed direct quantification of the introduced donor bacteria and of indigenous bacteria that had received the plasmids. The sprouts were observed for 9 days; during this time alfalfa seeds, inoculated with donor bacteria, developed to edible and subsequently decaying sprouts. The first transconjugants were detected on day 6 after donor inoculation and occurred at frequencies of 3.4 x 10(-4) and 2.0 x 10(-6) transconjugant cells per donor cell for pKJK5::gfp and TOL::gfp, respectively. Confocal laser scanning microscopy revealed that the sprouts were heavily colonized with donors and that most transconjugants were located around the hypocotyl and root areas. Randomly selected members of the indigenous bacterial community from both inoculated and uninoculated sprouts, as well as a representative part of the community that had received the plasmids, were characterized by polymorphisms of PCR-amplified ribosomal DNA (rDNA) spacer regions between the 16S and 23S genes, followed by partial 16S rDNA sequencing. This showed that the initially dominating genera Erwinia and Paenibacillus were gradually replaced by Pseudomonas on the fully developed sprouts. Transconjugants carrying either of the investigated plasmids mainly belonged to the genera Pseudomonas and ERWINIA: The numbers of transconjugant cells did not reach detectable levels until 6 days after the onset of germination, at which point these species constituted the majority of the indigenous bacteria. In conclusion, the alfalfa sprouts provided an environment that allowed noteworthy frequencies of plasmid transfer from P. putida in the absence of selective pressure that could favor the presence of the investigated plasmids.
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Affiliation(s)
- Lars Mølbak
- Department of Environmental Chemistry and Microbiology, National Environmental Research Institute, DK-4000 Roskilde, Danish Veterinary and Food Administration, 2860 Søborg, Denmark
| | - Tine Rask Licht
- Department of Environmental Chemistry and Microbiology, National Environmental Research Institute, DK-4000 Roskilde, Danish Veterinary and Food Administration, 2860 Søborg, Denmark
- Corresponding author. Mailing address: Danish Veterinary and Food Administration, Mørkhøj Bygade 19, 2860 Søborg, Denmark. Phone: 45-33-95-61-86. Fax: 45-33-95-66-98. E-mail:
| | - Thomas Kvist
- Department of Environmental Chemistry and Microbiology, National Environmental Research Institute, DK-4000 Roskilde, Danish Veterinary and Food Administration, 2860 Søborg, Denmark
| | - Niels Kroer
- Department of Environmental Chemistry and Microbiology, National Environmental Research Institute, DK-4000 Roskilde, Danish Veterinary and Food Administration, 2860 Søborg, Denmark
| | - Sigrid Rita Andersen
- Department of Environmental Chemistry and Microbiology, National Environmental Research Institute, DK-4000 Roskilde, Danish Veterinary and Food Administration, 2860 Søborg, Denmark
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Smets BF, Morrow JB, Arango Pinedo C. Plasmid introduction in metal-stressed, subsurface-derived microcosms: plasmid fate and community response. Appl Environ Microbiol 2003; 69:4087-97. [PMID: 12839785 PMCID: PMC165196 DOI: 10.1128/aem.69.7.4087-4097.2003] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nonconjugal IncQ plasmids pMOL187 and pMOL222, which contain the metal resistance-encoding genes czc and ncc, were introduced by using Escherichia coli as a transitory delivery strain into microcosms containing subsurface-derived parent materials. The microcosms were semicontinuously dosed with an artificial groundwater to set a low-carbon flux and a target metal stress (0, 10, 100, and 1,000 micro M CdCl(2)), permitting long-term community monitoring. The broad-host-range IncPalpha plasmid RP4 was also transitorily introduced into a subset of microcosms. No novel community phenotype was detected after plasmid delivery, due to the high background resistances to Cd and Ni. At fixed Cd doses, however, small but consistent increases in Cd(r) or Ni(r) density were measured due to the introduction of a single pMOL plasmid, and this effect was enhanced by the joint introduction of RP4; the effects were most significant at the highest Cd doses. The pMOL plasmids introduced could, however, be monitored via czc- and ncc-targeted infinite-dilution PCR (ID-PCR) methods, because these genes were absent from the indigenous community: long-term presence of czc (after 14 or 27 weeks) was contingent on the joint introduction of RP4, although RP4 cointroduction was not yet required to ensure retention of ncc after 8 weeks. Plasmids isolated from Ni(r) transconjugants further confirmed the presence and retention of a pMOL222-sized plasmid. ID-PCR targeting the RP4-specific trafA gene revealed retention of RP4 for at least 8 weeks. Our findings confirm plasmid transfer and long-term retention in low-carbon-flux, metal-stressed subsurface communities but indicate that the subsurface community examined has limited mobilization potential for the IncQ plasmids employed.
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Affiliation(s)
- Barth F Smets
- Environmental Engineering Program, Department of Civil and Environmental Engineering, University of Connecticut, 261 Glenbrook Road, Storrs, CT 06269-2037, USA.
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16
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Christensen BB, Sternberg C, Andersen JB, Molin OS. In situ detection of gene transfer in a model biofilm engaged in degradation of benzyl alcohol. APMIS. SUPPLEMENTUM 1998; 84:25-8. [PMID: 9850678 DOI: 10.1111/j.1600-0463.1998.tb05644.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- B B Christensen
- Department of Microbiology, Technical University of Denmark, Lyngby, Denmark
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Christensen BB, Sternberg C, Andersen JB, Eberl L, Moller S, Givskov M, Molin S. Establishment of new genetic traits in a microbial biofilm community. Appl Environ Microbiol 1998; 64:2247-55. [PMID: 9603843 PMCID: PMC106307 DOI: 10.1128/aem.64.6.2247-2255.1998] [Citation(s) in RCA: 194] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Conjugational transfer of the TOL plasmid (pWWO) was analyzed in a flow chamber biofilm community engaged in benzyl alcohol degradation. The community consisted of three species, Pseudomonas putida RI, Acinetobacter sp. strain C6, and an unidentified isolate, D8. Only P. putida RI could act as a recipient for the TOL plasmid. Cells carrying a chromosomally integrated lacIq gene and a lacp-gfp-tagged version of the TOL plasmid were introduced as donor strains in the biofilm community after its formation. The occurrence of plasmid-carrying cells was analyzed by viable-count-based enumeration of donors and transconjugants. Upon transfer of the plasmids to the recipient cells, expression of green fluorescence was activated as a result of zygotic induction of the gfp gene. This allowed a direct in situ identification of cells receiving the gfp-tagged version of the TOL plasmid. Our data suggest that the frequency of horizontal plasmid transfer was low, and growth (vertical transfer) of the recipient strain was the major cause of plasmid establishment in the biofilm community. Employment of scanning confocal laser microscopy on fixed biofilms, combined with simultaneous identification of P. putida cells and transconjugants by 16S rRNA hybridization and expression of green fluorescence, showed that transconjugants were always associated with noninfected P. putida RI recipient microcolonies. Pure colonies of transconjugants were never observed, indicating that proliferation of transconjugant cells preferentially took place on preexisting P. putida RI microcolonies in the biofilm.
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Affiliation(s)
- B B Christensen
- Department of Microbiology, The Technical University of Denmark, DK-2800 Lyngby, Denmark
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