Several Polysaccharides are involved in cell to cell interactions and biofilm formation in Rhizobium leguminosarum bv. viciae.

RUSSO, DM; WILLIAMS, A.; DOWNIE, JA Y ZORREGUIETA, A.

Puerto Iguazú, Misiones, Argentina

Congreso; XL Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB).; 2004

Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB).

SEVERAL POLYSACCHARIDES ARE INVOLVED IN CELL TO CELL INTERACTIONS AND BIOFILM FORMATION IN RHIZOBIUM LEGUMINOSARUM BV. VICIAE Russo, Daniela M.; Williams, Alan(*); Downie, J. Allan(*) and Zorreguieta, Angeles. IIB-FCEN, UBA; Fundación Instituto Leloir, Bs.As., Argentina and (*) John Innes Centre, Norwich, U.K. E-mail: drusso@leloir.org.ar Our previous results indicated that Rhizobium leguminosarum bv. viciae 8401 pRL1JI is capable of forming a three-dimensional structure known as biofilm on minimal medium. This bacterial behaviour could be advantageous for rhizobial survival and promoting root hair attachment. Confocal laser scanning microscopy was used to visualise the different events of biofilm formation with GFP-labelled bacteria in chambered coverglass slides. The PrsDE system is responsible for secretion of several proteins including the glycanases PlyB and PlyA and three adhesins. We have previously shown that mutations in prsD, prsE or plyB severely affect biofilm maturation. The exopolysaccharide (EPS) and cellulose are both substrates of PlyB and PlyA. A mutant in pssA, a crucial gene for the EPS synthesis was unable to develop a biofilm although tight cell-to-cell interactions were observed in bacterial clumping. An additional mutation in celA, which encodes the cellulose synthase abolished clump formation in the pssA mutant, indicating that cellulose synthesis is crucial in clumping. Interestingly, the O antigen region of LPS contributes to lateral cell-to-cell interactions and it is essential in biofilm formation. Our results indicate that in Rhizobium leguminosarum multiple surface and extracellular factors participate in modulation of biofilm structure.