Desarrollo de una herramienta molecular para la detección de transferencia horizontal de plásmidos desde Sinorhizobium meliloti a receptores potenciales presentes en el suelo

TORRES TEJERIZO, G.,GIUSTI M.Á., LOZANO M., DRAGHI W., LAGARES A Y PISTORIO M.

Los cocos, Cordoba, Argentina

Congreso; XXIII Reunión Latinoamericana de Rizobiología; 2007

Asociación Latinoamericana de Rhizobiología

A significant amount of practical and fundamental knowledge on the biology of the rhizobium-legume symbioses has been gathered over the years allowing this association to become a model system for the study of other plant-microbe interactions. The study of the establishment of rhizobia inoculated into natural soils, their rhizosphere colonization, nodule occupancy, and putative exchange of genetic traits with other soil bacteria all require the use of properly tagged genetic elements and strains for their unequivocal recognition in highly biodiverse environments. We present here a genetic system to specifically detect the transfer of tagged plasmids from known donor rhizobia to recipient bacteria in the environment. The modification of an experimental design originally set up in E.coli allows for the detection of horizontal plasmid transfer events based on the appearance of a green-fluorescent phenotype in the (otherwise dark) transconjugants. A plasmid-borne lac promoter-gfp fusion is repressed in the donor rhizobia by a highly expressed chromosomal LacI (nptII promoter). The GFP escapes then the repression upon transfer of the labeled plasmid, and replication in a new host bacterium.