Detection of Plasmid Transfer from Pseudomonas fluorescens to Indigenous Bacteria in Soil by Using Bacteriophage phiR2f for Donor Counterselection.
The transfer of a genetically marked derivative of plasmid RP4, RP4p, from Pseudomonas fluorescens to members of the indigenous microflora of the wheat rhizosphere was studied by using a bacteriophage that specifically lyses the donor strain and a specific eukaryotic marker on the plasmid. Transfer of RP4p to the wheat rhizosphere microflora was observed, and the number of transconjugants detected was approximately 10 transconjugants per g of soil when 10 donor cells per g of soil were added; transfer in the corresponding bulk soil was slightly above the limit of detection. All of the indigenous transconjugants which we analyzed contained a 60-kb plasmid and were able to transfer this plasmid to a Nx RpP. fluorescens recipient strain. The indigenous transconjugants were identified as belonging to Pseudomonas spp., Enterobacter spp., Comamonas spp., and Alcaligenes spp.
Smit
E
E
Institute for Soil Fertility Research, P.O. Box 48, 6700 AA Wageningen, and Microbiology Department, Agricultural University of Wageningen, 6703 CT Wageningen, The Netherlands.
van Elsas
J D
JD
van Veen
J A
JA
de Vos
W M
WM