Uesugi S L, Yarwood R R, Selker J S, Bottomley P J
Department of Crop and Soil Sciences, Oregon State University, Corvallis, OR 97331-3804, USA.
J Microbiol Methods. 2001 Dec;47(3):315-22. doi: 10.1016/s0167-7012(01)00337-2.
A cooled charge-coupled device (CCD) camera was used to follow the kinetics of induction of lux gene-dependent bioluminescence in Pseudomonas fluorescens HK44 held either in aqueous suspensions minus sand, saturated or unsaturated translucent sand (0.348 and 0.07 cm(3) H(2)O/cm(3) of sand, respectively), and at cell densities ranging between 1 x 10(6) and 8.5 x 10(8) cells/ml. Before O(2) availability became a limiting factor, the rate of light emission (L) increased with the square of time (t) and linearly with increasing cell density (c). A nonlinear model was developed that contains a "rate of increase in light emission" constant, B', which is determined directly from the slope of a plot of radical L/c against t. The model predicted the behavior of lux induction in HK44 under a variety of conditions. Similar B' values were determined [49.0-57.6 x 10(-10) light units/(cell min(2))] for cell suspensions held in aqueous medium minus sand, in saturated or unsaturated 40/50 grade sand (0.36 mm grain diameter) and in two other textural classes of translucent sand. Although both the growth phase, and the presence of glucose during lux induction affected the first detectable time (FDT) of bioluminescence by HK44 in sand, the kinetics of induction of light emission were similar among treatments (stationary phase cells plus glucose, B'=61.6+/-3.2, log phase cells plus glucose, B'=63.2+/-7.2). The potential exists to use a combination of a CCD camera system, an inducible lux gene containing bioluminescent bacterium, and a light transmission chamber to nonintrusively visualize and quantify in real time the interactions between bacterial growth and unsaturated flow of water and solutes in porous media.
使用冷却的电荷耦合器件（CCD）相机跟踪荧光假单胞菌HK44中lux基因依赖性生物发光诱导的动力学，该菌分别保存在不含沙子的水悬浮液、饱和或不饱和半透明沙子（分别为0.348和0.07 cm³ H₂O/cm³沙子）中，细胞密度范围为1×10⁶至8.5×10⁸个细胞/ml。在氧气供应成为限制因素之前，发光速率（L）随时间（t）的平方增加，并随细胞密度（c）的增加呈线性增加。开发了一个非线性模型，该模型包含一个“发光增加速率”常数B'，它直接由√L/c对t的图的斜率确定。该模型预测了HK44在各种条件下的lux诱导行为。对于保存在不含沙子的水介质、饱和或不饱和40/50级沙子（粒径0.36 mm）以及其他两种质地类别的半透明沙子中的细胞悬浮液，确定了相似的B'值[49.0 - 57.6×10⁻¹⁰光单位/（细胞·分钟²）]。尽管生长阶段以及lux诱导过程中葡萄糖的存在都会影响HK44在沙子中生物发光的首次可检测时间（FDT），但各处理之间发光诱导的动力学相似（稳定期细胞加葡萄糖，B' = 61.6±3.2，对数期细胞加葡萄糖，B' = 63.2±7.2）。存在使用CCD相机系统、含有可诱导lux基因的生物发光细菌和光传输室的组合来非侵入性地实时可视化和量化细菌生长与多孔介质中水分和溶质不饱和流动之间相互作用的潜力。
