Van de Merwe W P, Li Z Z, Bronk B V, Czégé J
Biomedical Instrumentation Center, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799, USA.
Biophys J. 1997 Jul;73(1):500-6. doi: 10.1016/S0006-3495(97)78088-3.
The effect of changing growth conditions on the diameter of rod-shaped bacteria was studied in vivo with the use of polarized light scattering. The value of a ratio of scattering matrix elements was measured as a function of scattering angle at various times after nutritional "upshift" for two strains of Escherichia coli cells. The peak locations of the scattering function were calibrated against the diameter for rod-shaped bacteria. The peaks moved toward smaller angles as a function of time after upshift, indicating that the diameter was increasing. Under special conditions, substantial peak shifts occurred within a few minutes of growth condition change, indicating a rapid onset of growth in diameter. The rate of increase of the diameters after upshift was obtained from the angular shift of peak location. This rate was approximately 14 nm/min for E. coli K12 and approximately 9 nm/min for E. coli B/r at 37 degrees C. The rate of diameter increase is smaller at lower temperatures. Experiments with Bacillus megaterium showed that any diameter change after nutritional upshift at 37 degrees C is limited to at most a very small increase, at least for the strain and medium tested.
利用偏振光散射技术在体内研究了生长条件变化对杆状细菌直径的影响。对于两株大肠杆菌细胞，在营养“上调”后的不同时间，测量了散射矩阵元素比值随散射角的变化情况。针对杆状细菌，将散射函数的峰值位置根据直径进行校准。上调后，峰值随时间向较小角度移动，表明直径在增加。在特殊条件下，生长条件改变后几分钟内就会出现显著的峰值移动，表明直径迅速开始生长。上调后直径的增加速率可从峰值位置的角度移动得出。在37℃时，大肠杆菌K12的增加速率约为14nm/分钟，大肠杆菌B/r的增加速率约为9nm/分钟。在较低温度下，直径增加速率较小。巨大芽孢杆菌的实验表明，在37℃营养上调后，至少对于所测试的菌株和培养基，直径的任何变化最多限于非常小的增加。
