INSTITUTO DE BIOTECNOLOGIA Y BIOLOGIA MOLECULAR
Unidad Ejecutora - UE
congresos y reuniones científicas
From time to time the same questions: ?Who? are rhizobia?, What do they do?, How actively they evolve?.....static pictures for moving genomes?
LAGARES, A.; DEL PAPA, M.F.; PISTORIO, M.; DRAGHI, W. O.; LOZANO, M. J.; GIUSTI, M. A.; TORRES TEJERIZO, G. A.; SALAS, M, E.; MARTINI, C; LÓPEZ, J. L.; SALTO, I. P.
Mar del Plata
Conferencia; VIII Congreso Argentio de Microbiología General; 2012
Bacteria colonize quite diverse environments and are well recognized by their remarkable capacity to sense, adapt, and respond to different (and in cases challenging) extracellular conditions. While cells in multicellular organisms evolved to perform specific functions under carefully controlled conditions (homeostasis), bacteria -as unicellular organisms- learned on how to live most of their life time under changing and frequently contrasting environments. For these reasons, bacteria represent valuable systems to investigate strategies of short and long term processes of adaptation. In this context of analysis, bacteria with both free- and associative-style of life provide extraordinary possibilities to investigate how cells cyclically accommodate to contrasting extracellular conditions. In our laboratory we study since more than two decades the biology and biochemistry of rhizobia; gram negative bacteria that live in the underground and associate with the roots of legumes where they fix atmospheric nitrogen receiving and, in turn, use photosynthetic carbon. We will present with their pros and cons- classical and modern experimental approaches to characterize adaptive responses of rhizobia to stressing environments. We will discuss what we learned on transient adaptive responses to stress, how they affect the free living and the symbiosis, and the possibilities to explore their practical use for a better formulation of biofertilizers. Finally, we will discuss the use of genome-wide comparative genomic analyses to investigate long-term changes in rhizobia, and their associated behavioral consequences. We will analyze the general mechanisms that model rhizobial diversification, and show how they are evident with data that we collected from the analysis of chromosomes and plasmids (sym and cryptic) in the Medicago spp.-nodulating rhizobia. Evidences currently available on the rhizobial genomics will be discussed to help the audience thinking on the identity and diversity of the legume nodulating bacteria.