Analysis of a Pool of Small Plasmids from Soil Heterotrophic Cultivable Bacterial Communities
Maria Cristiana Papaleo 1, Marco Fondi 1, Isabel Maida 1, Elena Perrin 1, Annamaria Bevivino 2, Claudia Dalmastri 2, Renato Fani *, 1
1 Laboratory of Microbial and Molecular Evolution, Department of Biology, University of Florence, Via Madonna del Piano 6, I-50019 Sesto Fiorentino (Florence), Italy
2 Technical Unit for Sustainable Development and Innovation of Agro-Industrial System, ENEA Casaccia Research Center, Via Anguillarese 301, 00123 Rome, Italy
In this work the analysis of the plasmid presence on soil aerobic cultivable heterotrophic bacterial communities was carried out checking a panel of 1,200 isolates, in order to establish the frequency of plasmid presence as well as the degree of plasmid flow between strains affiliated to the same or different taxon. Bacterial communities were isolated from two different sites of a 13-year experimental field with a clay-silt texture. Plasmid molecules were detected at low frequency (27 isolates, 2%) with a size ranging between 2 Kb and 40 Kb. The RAPD analysis performed on the plasmid-harboring isolates and the phylogenetic analysis of the whole community using the 16S rRNA gene sequences revealed the existence of transfer of the same plasmids between strains belonging to the same species and, in some cases, to different species of the same genus. As it might be expected, even though the viable cells title did not differ significantly between the two samplings, the overall data disclosed an uneven distribution of both species and plasmid-harboring strains.
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* Address correspondence to this author at the Laboratory of Microbial and Molecular Evolution, Department of Biology, University of Florence, Via Madonna del Piano 6, I-50019 Sesto Fiorentino (Florence), Italy;
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