Roles of rhizobial surface components on protection against environmental stresses

NOCELLI, N., BOGINO, P.C., ABOD A., PERUSIA, P., SORROCHE, F., OTERO, L.H., GIORDANO, W.

Córdoba

Congreso; Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB),; 2016

Bacterial surfacecomponents and extracellular compounds, particularly flagella, lipopolysaccharides(LPSs), and exopolysaccharides (EPSs), in combination with environmental signals,play crucial roles in bacterial autoaggregation, biofilm development, survival,and host colonization. Ensifer meliloti, amodel alphaproteobacteria, producestwo symbiosis-promoting EPSs: succinoglycan (EPS I) and galactoglucan (EPS II).Studies of the E. meliloti/alfalfasymbiosis model system have revealed numerous biological functions of EPSs,including host specificity, participation in early stages of host plantinfection, signaling molecule during plant development, and protection fromenvironmental stresses. We evaluated functions of EPSs, LPSs and flagella, inbacterial resistance to heavy metals and metalloids, which are known to affectvarious biological processes. The results show thatmutations in these Rhizobial surface components affectthe normal development of resistance to E.meliloti. Specifically the synthesis of EPS II would be as a mechanism ofresistance to exposure to toxic metals, probably through different effects suchas trapping the metal outside the cells and/or formation of biofilm. Ourobservations demonstrate that surface componentsplay major roles in rhizobacterial survival.