Department of Applied Microbiology and Food Science, University of Saskatchewan, S7N 0W0, Saskatoon, Saskatchewan, Canada.
Microb Ecol. 1989 Jul;18(1):1-19. doi: 10.1007/BF02011692.
Computer-enhanced microscopy (CEM) was used to monitor bacteria colonizing the inner surfaces of a 1×3 mm glass flow cell. Image analysis provided a rapid and reliable means of measuring microcolony count, microcolony area, and cell motility. The kinetics of motile and nonmotilePseudomonas fluorescens surface colonization were compared at flow velocities above (120μm sec(-1)) and below (8μm sec(-1)) the strain's maximum motility rate (85μm sec(-1)). A direct attachment assay confirmed that flagellated cells undergo initial attachment more rapidly than nonflagellated cells at high and low flow. During continuous-flow slide culture, neither the rate of growth nor the timing of recolonization (cell redistribution within surface microenvironments) were influenced by flow rate or motility. However, the amount of reattachment of recolonizing cells was both flow and motility dependent. At 8μm sec(-1) flow, motility increased reattachment sixfold, whereas at 120μm sec(-1) flow, motility increased reattachment fourfold. The spatial distribution of recolonizing cells was also influenced by motility. Motile cells dispersed over surfaces more uniformly (mean distance to the nearest neighbor was 47.0μm) than nonmotile cells (mean distance was 14.2μm) allowing uniform biofilm development through more effective redistribution of cells over the surface during recolonization. In addition, motile cell backgrowth (where cells colonize against laminar flow) occurred four times more rapidly than nonmotile cell backgrowth at low flow (where rate of motility exceeded flow), and twice as rapidly at high flow (where flow exceeded the rate of motility). The observed backgrowth of Mot(+) cells against high flow could only have occurred as the result of motile attachment behavior. These results confirm the importance of motility as a behavioral mechanism in colonization and provides an explanation for enhanced colonization by motile cells in environments lacking concentration gradients necessary for chemotactic behavior.
计算机增强显微镜（CEM）用于监测内表面玻璃流动细胞内定殖的细菌。图像分析提供了一种快速可靠的方法来测量微菌落计数，微菌落面积和细胞运动性。在高于（120μm sec(-1))和低于（8μm sec(-1))菌株最大运动速度（85μm sec(-1))的流速下，比较了运动和非运动荧光假单胞菌表面定植的动力学。直接附着测定证实，在高流速和低流速下，鞭毛细胞比非鞭毛细胞更快地进行初始附着。在连续流动滑动培养中，流速或运动性都不会影响生长速率或再殖民化的时间（表面微环境内细胞的重新分布）。然而，再殖民化细胞的再附着量取决于流速和运动性。在 8μm sec(-1)流速下，运动性使再附着增加了六倍，而在 120μm sec(-1)流速下，运动性使再附着增加了四倍。再殖民化细胞的空间分布也受到运动性的影响。运动性细胞在表面上更均匀地分散（最近邻居的平均距离为 47.0μm），而非运动性细胞（平均距离为 14.2μm），从而在再殖民化过程中通过更有效地在表面上重新分配细胞，从而实现均匀的生物膜发育。此外，在低流速（运动速度超过流速）下，运动细胞的反向生长（细胞在层流中定殖）比非运动细胞的反向生长快四倍，在高流速（流速超过运动速度）下，反向生长快两倍。在高流速下观察到的 Mot(+)细胞的反向生长只能是由于运动性附着行为所致。这些结果证实了运动性作为定殖行为机制的重要性，并为在缺乏趋化性行为所需浓度梯度的环境中，运动性细胞增强定殖提供了解释。
