Physico-chemical surface properties of rhizobacteria and their adhesion to rice roots

Abstract The aim of this work was to assess the involvement of surface charge and hydrophobicity in the initial stages of rhizobacterial adhesion to rice roots. To this purpose, the cell surface properties of axenic rice roots and of ten rhizobacterial strains belonging to various genera isolated from wheat, rice and maize roots were established. The electrophoretic potential and the streaming potential were measured in 0.01 M KC1, for the cells and the roots, respectively. The rice roots exhibited a negative potential (around - 6 mV) at pH above 4. The bacteria also exhibited a negative potential spread from - 2 to - 38 mV in the same pH range. The hydrophobicity of the cell surface was measured by bacterial adhesion to hydrocarbon (hexane) and to polystyrene. Hydrophobic adhesion to polystyrene was hindered by high negative Ξ potentials. Adhesion to rice roots correlated well with adhesion to polystyrene.