Cell surface hydrophobicity of Ralstonia solanacearum

Abstract:

Bacterial adhesion to hydrocarbons (BATH) and hydrophobic interaction chromatography (HIC) were employed to determine cell surface hydrophobicity (CSH) of Ralstonia solanacearum, respectively. The effects of the ratio of bacterial suspension to n-dodecane in the BATH assays and the injection volume of bacterial suspension in the HIC assays on the measurement of CSH were investigated. The optimal conditions for CSH analysis were as follow: the ratio of bacterial suspension (OD₆₀₀=0.5) to n-dodecane was 2:1 and the injection volume of bacterial suspension (OD₆₀₀=1.0) was 0.2 mL. Under these conditions, a good linear relationships between BATH and HIC methods was obtained (r=0.99). Moreover, HIC method was applied to detect the variation of CSH during growth of Ralstonia solanacearum. The results indicated that the CSH decreased with culture time and approached a plateau after 24 h of incubation, and a negative correlation between CSH and EPSⅠ (extracellular polysaccharide) content of cell surface was observed. The experimental results of three Ralstonia so-lanacearum stains of different virulence further confirmed that the CSH decreased with increasing EPSⅠcontent.

Key words:Ralstonia solanacearum;Cell surface;Hydrophobicity;EPSⅠcontent