THE INFLUENCE OF THE CELL SUSPENSION REDOX POTENTIAL ON THE CAPACITY OF XYLELLA FASTIDIOSA TO AGGREGATE

• Author(s): Andersen, Peter; Leite, Breno;
• Abstract: The Calcium Bridging Hypothesis (CBH) implies that surface redox changes on cells of Xylella fastidiosa (Xf) may influence the capacity of these cells to aggregate. A series of experiments were designed to challenge the proposed CBH. In this hypothesis, thiols (SH) located at the outer membrane level or in adhesion related structures of Xf could increase or decrease the cells attraction to the xylem wall surface and/or other Xf cells. The focus of this investigation was to address the possibility to alter the surface status of SH groups by exposing cells to reduced and oxidized forms of the tripeptide gluthathione (commonly found in xylem fluid). CBH also assumes that divalent ions would mediate the interaction between thiols and other negative charges. Xf aggregation was measured after the following treatments: deionized water (negative (control), CaCl)2 100 mg/L (positive control), reduced glutathione 10 mM (GSH), oxidized glutathione 10 mM (GSSG), GSH (10 M for 20 min + CaCl)2 50 mg/L and GSSG 10 mM for 20 min + 50 mg/L. Maximum aggregation was obtained with pre-(treatment with GSH 10 mM for 20 min followed by exposure of cells to CaCl)2 (50 mg/L. Results indicate that a reducing) environment is essential for cell aggregation. A reducing environment apparently modified the surface of Xf cells and predisposed them to interact with divalent ions.
• Publication Date: Dec 2005
• Journal: 2005 Pierce's Disease Research Symposium