Biofilm matrix formation is modulated by a family of extracellular lectins in Rhizobium leguminosarum

VOZZA, NF.; RUSSO, DM.; ABDIAN, PL.; ZORREGUIETA, A.

Villa General Belgrano

Simposio; GlycoAR 2016. Second Argentinean Glycobiology Symposium.; 2016

FIL-CIQUIBIC-IBYME-Sociedad Latinoamericana de Glicobiologia

In nature, most microorganisms live in biofilms that are defined as cellular aggregates, adhered to a surface and encased in a self-produced complex matrix. The matrix is responsible for the physical integrity of the community, the adhesion to the surface, and cohesion between cells, but also acts as an external digestive system keeping extracellular enzymes close to the cells. Several extracellular factors involved in Rhizobium leguminosarum biofilm matrix formation have been identified. Among them, the acidic polysaccharides (exo- and capsular polysaccharides) as well as a family of extracellular proteins, termed Raps (Rhizobium adhering proteins) are key factors for biofilm formation. By means of genetic, biochemical and biophysical studies on matrix components, polysaccharide AFM analysis and imaging of biofilm formation by CLSM and SEM, we gained insight into mechanistic aspects of matrix formation. We propose that a particular organization of the acidic exopolysaccharide forming ordered meshes provides the structural basis for R. leguminosarum biofilm development, that these meshes depend on the correct processing of the acidic polysaccharide, and that the Rap proteins are directly involved in the modulation of the polysaccharide matrix.