Department of Chemical Engineering and Center for Soft Matter and Biological Physics , Virginia Tech , Blacksburg , Virginia 24061 , United States.
Department of Physics , Emory University , Atlanta , Georgia 30322 , United States.
ACS Appl Mater Interfaces. 2018 Mar 21;10(11):9225-9234. doi: 10.1021/acsami.7b16715. Epub 2018 Mar 8.
We demonstrate that the surface motility of the bacterium, Pseudomonas aeruginosa, is hindered by a crystalline hemispherical topography with wavelength in the range of 2-8 μm. The motility was determined by the analysis of time-lapse microscopy images of cells in a flowing growth medium maintained at 37 °C. The net displacement of bacteria over 5 min is much lower on surfaces containing 2-8 μm hemispheres than on flat topography, but displacement on the 1 μm hemispheres is not lower. That is, there is a threshold between 1 and 2 μm for response to the topography. Cells on the 4 μm hemispheres were more likely to travel parallel to the local crystal axis than in other directions. Cells on the 8 μm topography were less likely to travel across the crowns of the hemispheres and were also more likely to make 30°-50° turns than on flat surfaces. These results show that surface topography can act as a significant barrier to surface motility and may therefore hinder surface exploration by bacteria. Because surface exploration can be a part of the process whereby bacteria form colonies and seek nutrients, these results help to elucidate the mechanism by which surface topography hinders biofilm formation.
我们证明，细菌 Pseudomonas aeruginosa 的表面迁移运动受到具有 2-8 μm 波长的结晶半球形形貌的阻碍。通过分析在 37°C 下保持流动生长培养基中的细胞的延时显微镜图像来确定迁移运动。在含有 2-8 μm 半球的表面上，细菌在 5 分钟内的净位移远低于平面形貌，但在 1 μm 半球上的位移没有降低。也就是说，对形貌的响应存在 1 到 2 μm 的阈值。在 4 μm 半球上的细胞更有可能平行于局部晶体轴移动，而不是沿其他方向移动。在 8 μm 形貌上的细胞不太可能穿过半球的冠部移动，并且比在平面上更容易发生 30°-50°转弯。这些结果表明，表面形貌可以作为表面迁移运动的重要障碍，因此可能会阻碍细菌的表面探索。由于表面探索可能是细菌形成菌落和寻找营养物质的过程的一部分，因此这些结果有助于阐明表面形貌阻碍生物膜形成的机制。
