IIBBA   05544
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
“Role of RapA1 in cellular interactions during biofilm formation by Rhizobium leguminosarum”
Autor/es:
VOZZA, N; MORGIARDINI, E; RUSSO, D. M.; ABDIAN, P; LODEIRO A; ZORREGUIETA A
Lugar:
Villa Carlos Paz, Córdoba
Reunión:
Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular SAIB; 2008
Institución organizadora:
SAIB
Resumen:
It is widely accepted that many bacteria grow in the form of biofilms. Either spontaneously or by environmental pressure, bacteria associate to produce complex structures, usually embedded in exopolymers. Rhizobium leguminosarum was shown to form biofilms, and these biofilms are dependent on the presence of the type I protein secretion system PrsDE. Exopolysaccharides (EPS) play an important role in biofilm formation and several EPS-modifying enzymes are exported via PrsDE.  Besides, a family of proteins named Rhizobium adhering proteins (Raps) are also secreted by this system. Using confocal laser-scanning microscopy (CLSM) we sought to determine the role of RapA1 in biofilm formation. RapA1 was expressed in higher levels than wild type (4 to 5-fold) in 3 different strains of R. leguminosarum, and CLSM was used to follow biofilm formation in minimal medium (Y). Surprisingly, we observed that RapA1-overproducing strains have altered cell-to-cell interactions resulting in “less ordered”  biofilms. In addition, cells of RapA1 over-producing strains did not aggregate or settle from cultures when they were left standing. We also observed that in Y-Congo red plates, the colony morphology was altered when RapA1 was increased. We hypothesize that a specific amount of RapA1 on the cell surface is required for the cells to interact in the correct manner and form an “ordered” mature biofilm.