Plasmid mobilization from genetically engineered bacteria to members of the indigenous soil microflora in situ

Henschke, R. B.; Schmidt, Fr.

doi:10.1007/bf02092881

Cited by 98 publications

(54 citation statements)

References 23 publications

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“…Although plasmid transfer and mobilization under extreme oligotrophic conditions have been demonstrated (e.g., in rivers and seawater [7]), these experiments are often conducted with very high localized densities of donors and recipients and with broad-host-range conjugal plasmids (16,21), while transconjugants that are the result of mobilization of nonconjugal plasmids in the indigenous community are often only transiently observed (21,54). The strong dependency of the copy number on the joint introduction of RP4 strongly suggests that the poor establishment of the pMOL plasmids, when introduced by themselves, was in part due to the indigenous community's limited potential to mobilize these plasmids (53).…”

Section: Discussionmentioning

confidence: 99%

“…Because of its assumed importance in environmental settings (55), the focus was on conjugal plasmid transfer. Although examination of gene flow in natural microbial communities is experimentally difficult, several studies have demonstrated the occurrence of horizontal gene transfer in a variety of settings such as fresh waters (3,21) and soils (24,28,32). However, essentially no studies on horizontal gene transfer in subsurface microbial communities have been reported.…”

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confidence: 99%

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Plasmid Introduction in Metal-Stressed, Subsurface-Derived Microcosms: Plasmid Fate and Community Response

Smets

Morrow²,

Pinedo³

2003

Appl Environ Microbiol

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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 M CdCl 2 ), permitting long-term community monitoring. The broad-host-range IncP␣ 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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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Plasmid Introduction in Metal-Stressed, Subsurface-Derived Microcosms: Plasmid Fate and Community Response

Smets

Morrow²,

Pinedo³

2003

Appl Environ Microbiol

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“…Mobilization of GEMs to the indigenous soil microflora has been shown to occur in sitzi to P. jzlorescens (Henschke &Schmidt, 1990), andGenthner e t al. (1988) also demonstrated the ability of aquatic bacteria to act as recipients of the broad-host-range plasmids R68 and R1162.…”

Section: Discussionmentioning

confidence: 99%

Gene transfer in the aquatic environment: persistence and mobilization of the catabolic recombinant plasmid pD10 in the epilithon

1994

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This study investigated mobilization and persistence of the recombinant, catabolic plasmid pDlO in laboratory microcosms by natural mobilizing plasmids, recently isolated from epilithic bacteria by exogenous isolation in Pseudomonas putida, as opposed to their isolation in the strains in which they occur in situ. Initial experiments in simple, beaker microcosms were used to optimize conditions for selection of the donor, recipient and transconjugant populations. Studies in a recirculating stream microcosm showed that donor, P. putida KT2440(pDIO, pQKH6), and recipient, P. putida UWCG, populations, although declining with time, were able to survive for three weeks and that colonization and survival was predominantly in the epilithon of the microcosm rather than in the liquid phase. Transconjugants UWC6(pD10, pQKH6) were also isolated from epilithon, showing that plasmid pDlO had been mobilized b y plasmid pQKH6. The donor strain was able to survive a t 100-fold greater numbers than the recipient, but transconjugants were not isolated after day 15. Separate inoculation of the donor and recipient strains into the microcosm showed that they were able to colonize other stones, where transconjugants then arose as a direct result of plasmid transfer within the epilithon. A catechol2,3-dioxygenase gene, tdnC, was used to facilitate identification of donors and transconjugants. Preliminary laboratory matings showed that pDlO transferred to indigenous epilithic strains identified as Pseudomonas fluorescens, P. chlororaphis and P. aureofaciens. These results suggest that in the absence of selection, mobilization of introduced recombinant genes encoded by pDlO occurs at easily detectable frequencies, even in an oligotrophic environment.

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“…The potential for genetic exchange by conjugation, transduction and natural transformation has been demonstrated in a variety of diverse environments (Graham & Istock, 1978 ;Trevors & Oddie, 1986;Bale et al, 1987Bale et al, , 1988Rochelle et al, 1988;VanElsas et al, 1989;Fry & Day, 1990;Henschke & Schmidt, 1990;Paul et al, 1991 ;PretoriusGuth, 1990;Saye et al, 1990;Stewart & Sinigalliano, 1990 ;Klingmuller, 199 1). The occurrence of horizontal gene transfer events has been inferred by examining the distribution and genetic structure of specific phenotypes (e.g.…”

Section: Introductionmentioning

confidence: 95%

Factors affecting competence in a high frequency of transformation marine Vibrio

Frischer

Thurmond

Paul

1993

Journal of General Microbiology

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Natural plasmid transformation may be a mechanism for the horizontal transfer of non-conjugative plasmids in the marine environment, yet there are few marine model systems available for the study of this process. Using multimers of IncQ/P4 plasmids and a filter transformation assay, we have measured the effects of nutrients, salinity, temperature, as well as the development and maintenance of competence for genetic transformation in the high frequency of transformation (HFT) marine Vibrio strain WJT-1C. Transformation frequency was proportional to the amount of DNA used from 0.1 to 1.0 pg DNA and was saturated at concentrations greater than 1-0 pg. Competence began in the early-exponential phase and reached a maximum at the onset of stationary phase. Once attained, competence was maintained in both spent and nutrient-free media for at least 10 d. Thus, the establishment and maintenance of competence was unique compared to previously described transformation systems. Temperatures ranging from 4 to 33 "C had no significant effect on the maximal transformation frequency of WJT-lC, but at 37 "C the transformation frequency was reduced. However, temperature did affect the rate of the transformation process. Salinities in the range 12 to 50%, had no significant effect on the transformation frequency but transformation frequencies were lower at 6%, and 63%,. Cells were transformed equally well in nutrient-free media or rich media. The ability of this marine HF'T Vibrio strain to develop competence under a wide spectrum of conditions and to maintain the competent state indicates that natural plasmid transformation could occur in conditions found in tropical and subtropical estuaries.

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Plasmid mobilization from genetically engineered bacteria to members of the indigenous soil microflora in situ

Cited by 98 publications

References 23 publications

Plasmid Introduction in Metal-Stressed, Subsurface-Derived Microcosms: Plasmid Fate and Community Response

Plasmid Introduction in Metal-Stressed, Subsurface-Derived Microcosms: Plasmid Fate and Community Response

Gene transfer in the aquatic environment: persistence and mobilization of the catabolic recombinant plasmid pD10 in the epilithon

Factors affecting competence in a high frequency of transformation marine Vibrio

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