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.

Rosario

Congreso; LII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2016

Bacterial surface components 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, a model alphaproteobacteria, produces two symbiosis-promoting EPSs: succinoglycan (EPS I) and galactoglucan (EPS II). Studies of the E. meliloti/alfalfa symbiosis model system have revealed numerous biological functions of EPSs, including host specificity, participation in early stages of host plant infection, signaling molecule during plant development, and protection from environmental stresses. We evaluated functions of EPSs, LPSs and flagella, in bacterial resistance to heavy metals and metalloids, which are known to affect various biological processes. The results show that mutations in these Rhizobial surface components affect the normal development of resistance to E. meliloti. Specifically the synthesis of EPS II would be as a mechanism of resistance to exposure to toxic metals, probably through different effects such as trapping the metal outside the cells and/or formation of biofilm. Our observations demonstrate that surface components play major roles in rhizobacterial survival.