青枯菌细胞表面的疏水性

Cell surface hydrophobicity of Ralstonia solanacearum

分别采用BATH和HIC方法测定青枯菌细胞表面疏水性(CSH),并比较菌液与正十二烷比例(BATH方法)和菌液上样量(HIC方法)对CSH测定结果的影响。确定在BATH方法中菌液(OD600=0.5)与正十二烷的比例为2:1,HIC方法中菌液(OD600=1.0)上样量为0.2 mL;在此条件下,BATH和HIC两种方法之间呈现出良好的线性关系(r=0.99)。进一步采用HIC方法测定青枯菌在生长过程中CSH的变化情况,结果显示随培养时间的延长,CSH逐渐降低,24 h后CSH趋于稳定,CSH与青枯菌细胞表面的EPSⅠ(胞外酸性多糖)含量呈负相关。3株不同致病强度的青枯菌的试验结果进一步验证了青枯菌细胞表面的CSH随EPSⅠ含量的增加而降低。

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 solanacearum stains of different virulence further confirmed that the CSH decreased with increasing EPSⅠcontent.