Characterization of Ralstonia solanacearum in different growth phases by high performance ion exchange liquid chromatography analysis

Abstract:

High performance ion exchange liquid chromatography and laser light scattering instrument were employed to characterize Ralstonia solanacearum in different growth phases. The pure culture of Ralstonia solanacearum was successfully separated into three characteristic fractions. Chromatographic behaviors of Ralstonia solanacearum in lag phase, logarithmic phase and stationary phase were carefully investigated, and their relationships to the cell concentration, pH of fermentation broth and extracellular polysaccharide (EPSⅠ) content of cell surface were analyzed. It was found that the majority of Ralstonia solanacearum cells obtained at 8h culture time could not be absorbed to the resin due to the strong motility of the cells which could apparently overcome the electrostatic interaction. Furthermore, when the mobility of the cells was destroyed by 4% formaldehyde treatment, the prolonged retention time was recorded due to the stronger adsorbility to the resin. On the other hand, the EPSⅠ content of cell surface was determined to increase with the culture time, indicating an increasing interaction between the cells and the resin. EPSⅠ content of three characteristic chromatographic fractions was determined, and it was found that the higher EPSⅠ content led to the longer retention time of the fraction, which confirmed the above-mentioned observation. As a result, it is concluded that the formation of three chromatographic fractions of the pure culture of Ralstonia solanacearum is attributed to bacterial motility and the interaction of EPSⅠ of cell surface with the anionic exchange resin, and the novel method of ion exchange chromatography of the intact bacterial cells can be a useful tool in bacteriological study.