Deep sequencing of the cryptic plasmid mobilome in the symbiotic bacterium Sinorhizobium meliloti

LOPEZ J.L.; GIUSTI ,M.A.; MARTINI M.C.; TORRES TEJERIZO G; LOZANO, M. J.; SALAS, M.E.; SALTO I.; PUHLER, A.; DEL PAPA M. F.; SCHLÜTER A; PISTORIO M.; LAGARES A.

Santander

Conferencia; International Plasmid Biology Conference; 2012

International Plasmid Biology Society

Rhizobia are alfa- and beta- proteobacteria that inhabit soils, and are able to establish specific N2-fixing symbioses with legumes. Current information shows that rhizobia are significantly diverse including different bacterial genera, and that in several cases bear significant amounts of plasmid DNA ranging from few kilobases to megabases in size. Many of those plasmids are currently being characterized at the molecular level, and show to be active vectors for horizontal gene transfer (HGT) in the processes of rhizobial diversification/speciation (Cervantes et al. 2011; Torres Tejerizo et al. 2011). Methods. In a survey to investigate plasmid diversity in S. meliloti, the N2-fixing symbiont of alfalfa, we purified more than forty (mid- to high- molecular weight) cryptic plasmids which were used here to characterize, by deep sequencing, the mobilome gene content at the species level. Plasmids that sized approx. between 50-400 kb were prepared by CsCl gradients, sequenced using the Ion Torrent Technology, and the collected data analyzed via the metaSAMS software package. Results. We collected more than 0.5 Gb of non-redundant plasmid sequence data. The low contamination with 16S rDNA (