Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.
Biotechnol Bioeng. 1991 Apr 15;37(9):824-33. doi: 10.1002/bit.260370906.
The growth of immobilized Escherichia coli was analyzed by pulse-chase radioisotope labeling of the cell mass with (35)SO(4) (2-) and subsequent liquid emulsion autoradiography of thin cross sections of the cell aggregate. Bacteria were retained in a planar aggregate on a microporous membrane and grown anaerobically on a phosphate-buffered medium with glucose as the sole carbon and energy source. A mathematical model of immobilized cell growth and convection was used to predict the distribution of label in the cell mass and permit information about both the magnitude and variation in the intrinsic growth rate to be extracted. Growing zone dimensions ranging from 4 to 48 mum and growth rates from 0.28 to 0.5 h(-1) were found. Data collected at low glucose concentrations were consistent with a zero-order description of intrinsic growth kinetics. At high glucose concentrations, conditions under which the system was subject to significant pH inhibition, the data were best described by the prediction of a first-order kinetic model. When coupled with a suitable analytical framework, the combination of radioisotope labeling and autoradiography provides a general method for characterizing immobilized cell growth rates.
采用（35）SO4（2-）脉冲追踪放射性同位素标记细胞质量，并对细胞聚集体的薄截面进行液体乳胶放射自显影，分析固定化大肠杆菌的生长情况。细菌保留在微孔膜上的平面聚集体中，并在含有葡萄糖作为唯一碳源和能源的磷酸盐缓冲培养基中进行厌氧生长。使用固定化细胞生长和对流的数学模型来预测标记在细胞质量中的分布，并允许提取关于内在增长率的幅度和变化的信息。发现生长区尺寸范围从 4 到 48 微米，生长速率从 0.28 到 0.5 小时-1。在低葡萄糖浓度下收集的数据与内在生长动力学的零级描述一致。在高葡萄糖浓度下，系统受到显著 pH 抑制的条件下，数据通过预测一级动力学模型得到了最好的描述。当与合适的分析框架结合使用时，放射性同位素标记和放射自显影的组合为表征固定化细胞生长速率提供了一种通用方法。
