Chen Jui-Lin, Chiang Ming-Lun, Chou Cheng-Chun
Graduate Institute of Food Science and Technology, National Taiwan University, Taipei, Taiwan.
Foodborne Pathog Dis. 2009 May;6(4):453-60. doi: 10.1089/fpd.2008.0231.
In the present study, the foodborne pathogen Bacillus cereus 1-4-1 was subjected to acid adaptation treatment by suspending the test organism in tryptic soy broth (pH 5.5) for 2 hours. The susceptibility of the acid-adapted and nonadapted cells of B. cereus 1-4-1 to high concentrations of ethanol (20%) and NaCl (20%) was then examined. In addition, the effect of acid adaptation on the protein expression profile of B. cereus 1-4-1 as well as the growth patterns of the acid-adapted and nonadapted cells of the test organism in the presence of various carbon and nitrogen sources were compared. Results revealed that acid-adapted B. cereus 1-4-1 was more susceptible to ethanol (20%) and NaCl (20%) than its nonadapted counterpart. Analysis with one-dimensional SDS-PAGE showed no distinct difference in the expression of the 16 proteins bands noted in the nonadapted cells compared with those of acid-adapted cells. Two-dimensional electrophoresis revealed that the acid adaptation treatment affected the expression of 26 species of protein, with the levels of 12 proteins increasing and 14 proteins decreasing in the cells of acid-adapted B. cereus 1-4-1 compared with those of the control cells. Furthermore, immunoblotting detected GroEL-like protein with a similar level in the acid-adapted and nonadapted cells of B. cereus 1-4-1 while failing to find the presence of a DnaK-like protein. B. cereus 1-4-1, regardless of acid adaptation, exhibited the highest maximum growth with sucrose as the carbon source while the maximum growth was found in the presence of either peptone, soytone, tryptone, or yeast extract as the nitrogen source, with these showing no significant difference. Finally, the growth patterns of the acid-adapted and nonadapted cells were similar.
在本研究中，将食源性病原体蜡样芽孢杆菌1-4-1悬浮于胰蛋白胨大豆肉汤（pH 5.5）中2小时，进行酸适应性处理。然后检测了酸适应性和未适应性的蜡样芽孢杆菌1-4-1细胞对高浓度乙醇（20%）和氯化钠（20%）的敏感性。此外，还比较了酸适应性对蜡样芽孢杆菌1-4-1蛋白质表达谱的影响，以及在各种碳源和氮源存在下，受试生物体酸适应性和未适应性细胞的生长模式。结果显示，酸适应性蜡样芽孢杆菌1-4-1比未适应性的更易受乙醇（20%）和氯化钠（20%）影响。一维SDS-PAGE分析表明，与酸适应性细胞相比，未适应性细胞中所观察到的16条蛋白带的表达没有明显差异。二维电泳显示，酸适应性处理影响了26种蛋白质的表达，与对照细胞相比，酸适应性蜡样芽孢杆菌1-4-1细胞中有12种蛋白质水平升高，14种蛋白质水平降低。此外，免疫印迹检测到蜡样芽孢杆菌1-4-1酸适应性和未适应性细胞中GroEL样蛋白水平相似，而未发现DnaK样蛋白的存在。无论是否经过酸适应性处理，蜡样芽孢杆菌1-4-1以蔗糖作为碳源时表现出最高的最大生长速率，而以蛋白胨、大豆蛋白胨、胰蛋白胨或酵母提取物作为氮源时均出现最大生长，且这些氮源之间无显著差异。最后，酸适应性和未适应性细胞的生长模式相似。
