Previous Article | Next Article 
Applied and Environmental Microbiology, September 2003, p. 5536-5542, Vol. 69, No. 9
0099-2240/03/$08.00+0 DOI: 10.1128/AEM.69.9.5536-5542.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.
Plasmid Transfer from Pseudomonas putida to the Indigenous Bacteria on Alfalfa Sprouts: Characterization, Direct Quantification, and In Situ Location of Transconjugant Cells
Lars Mølbak,1 Tine Rask Licht,2* Thomas Kvist,2 Niels Kroer,1 and Sigrid Rita Andersen2Department of Environmental Chemistry and Microbiology, National Environmental Research Institute, DK-4000 Roskilde,1 Danish Veterinary and Food Administration, 2860 Søborg, Denmark2
Received 3 February 2003/ Accepted 9 June 2003
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.
* 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: trl{at}fdir.dk.
Applied and Environmental Microbiology, September 2003, p. 5536-5542, Vol. 69, No. 9
0099-2240/03/$08.00+0 DOI: 10.1128/AEM.69.9.5536-5542.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.
This article has been cited by other articles:
-
Toomey, N., Monaghan, A., Fanning, S., Bolton, D.
(2009). Transfer of Antibiotic Resistance Marker Genes between Lactic Acid Bacteria in Model Rumen and Plant Environments. Appl. Environ. Microbiol.
75: 3146-3152
[Abstract] [Full Text] -
Musovic, S., Oregaard, G., Kroer, N., Sorensen, S. J.
(2006). Cultivation-Independent Examination of Horizontal Transfer and Host Range of an IncP-1 Plasmid among Gram-Positive and Gram-Negative Bacteria Indigenous to the Barley Rhizosphere.. Appl. Environ. Microbiol.
72: 6687-6692
[Abstract] [Full Text] -
De Gelder, L., Vandecasteele, F. P. J., Brown, C. J., Forney, L. J., Top, E. M.
(2005). Plasmid Donor Affects Host Range of Promiscuous IncP-1{beta} Plasmid pB10 in an Activated-Sludge Microbial Community. Appl. Environ. Microbiol.
71: 5309-5317
[Abstract] [Full Text]
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»