Experimental Physics, Saarland University, Center for Biophysics, 66123 Saarbrücken, Germany.
Theoretical Physics, Saarland University, Center for Biophysics, 66123 Saarbrücken, Germany.
Soft Matter. 2024 Jan 17;20(3):484-494. doi: 10.1039/d3sm01045g.
Understanding and controlling microbial adhesion is a critical challenge in biomedical research, given the profound impact of bacterial infections on global health. Many facets of bacterial adhesion, including the distribution of adhesion forces across the cell wall, remain poorly understood. While a recent 'patchy colloid' model has shed light on adhesion in Gram-negative cells, a corresponding model for Gram-positive cells has been elusive. In this study, we employ single cell force spectroscopy to investigate the adhesion force of . Normally, only one contact point of the entire bacterial surface is measured. However, by using a sine-shaped surface and recording force-distance curves along a path perpendicular to the rippled structures, we can characterize almost a hemisphere of one and the same bacterium. This unique approach allows us to study a greater number of contact points between the bacterium and the surface compared to conventional flat substrata. Distributed over the bacterial surface, we identify sites of higher and lower adhesion, which we call 'patchy adhesion', reminiscent of the patchy colloid model. The experimental results show that only some cells exhibit particularly strong adhesion at certain locations. To gain a better understanding of these locations, a geometric model of the bacterial cell surface was created. The experimental results were best reproduced by a model that features a few (5-6) particularly strong adhesion sites (diameter about 250 nm) that are widely distributed over the cell surface. Within the simulated patches, the number of molecules or their individual adhesive strength is increased. A more detailed comparison shows that simple geometric considerations for interacting molecules are not sufficient, but rather strong angle-dependent molecule-substratum interactions are required. We discuss the implications of our results for the development of new materials and the design and analysis of future studies.
理解和控制微生物附着是生物医学研究中的一个关键挑战，因为细菌感染对全球健康有着深远的影响。细菌附着的许多方面，包括细胞壁上附着力的分布，仍然了解甚少。虽然最近的“斑状胶体”模型揭示了革兰氏阴性细胞的附着，但对于革兰氏阳性细胞，相应的模型仍然难以捉摸。在这项研究中，我们采用单细胞力谱法研究 的附着力。通常，仅测量整个细菌表面的一个接触点。然而，通过使用正弦形表面并沿着垂直于波纹结构的路径记录力-距离曲线，我们可以描述同一细菌的几乎半个半球。这种独特的方法使我们能够研究细菌与表面之间更多的接触点，与传统的平面基质相比。在细菌表面上分布的位置，我们确定了较高和较低附着的位置，我们称之为“斑状附着”，类似于斑状胶体模型。实验结果表明，只有一些细胞在某些位置表现出特别强的附着。为了更好地理解这些位置，我们创建了一个细菌细胞表面的几何模型。实验结果通过一个具有几个（5-6 个）特别强的附着位置（直径约 250nm）的模型得到了最好的再现，这些位置广泛分布在细胞表面。在模拟的斑块内，分子的数量或它们各自的粘附强度增加。更详细的比较表明，相互作用分子的简单几何考虑是不够的，而是需要强烈的依赖角度的分子-基质相互作用。我们讨论了我们的结果对新材料的开发以及未来研究的设计和分析的影响。
