Effect of hydrophobicity and divalent ions on biofilm formation of Xylella fastidiosa

• Author(s): Andersen, Peter; Ishida, Maria Lucia; Leite, Breno;
• Abstract: Pathogenicity of Xylella fastidiosa (Xf) is often correlated to the capacity of cells to adhere to the internal walls of xylem vessels, with subsequent formation of biofilm followed by vessel occlusion. The establishment of a biofilm requires: 1) adhesion of cells to a surface and 2) the build up of several layers of cells and cell products. These cells will produce and accumulate exopolysaccharides (EPS), contributing for the biofilm architecture. Cell surface hydrophobicity is considered an important component of cell adhesion. Our results concerning colony formation on chemically-defined media for X. f. are consistent with the hypothesis that X. f. pathogenicity may be affected by hydrophobicity. Some of the new media are highly hydrophobic, and X. f. colonies grown under these conditions produced more biofilm and aggregated into larger colonies compared hydrophilic media. Treatments with cations Ca++ and Mg++ increased hydrophobicity whereas NaCl and phosphates decreased it. Manipulation of media hydrophobicity may elucidate the relationship between hydrophobicity, cell surface chemistry and biofilm formation.
• Publication Date: Jun 2003
• Journal: Phytopathology