Eskhan Asma, Ramezanian Somayeh, Uzoechi Samuel, Abu-Lail Nehal I
Department of Chemical Engineering, Al-Balqa Applied University, P.O. Box 15008, Amman 11134, Jordan.
Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington 99164-6515.
Biointerphases. 2025 May 1;20(3). doi: 10.1116/6.0004587.
Forces acting between an atomic force microscopy silicon nitride cantilever and the bacterial surface biopolymers of Escherichia coli or Pseudomonas putida were spatially probed in water. The interactions were fitted to a model of steric repulsion to estimate the bacterial surface biopolymer brush length and grafting density. The forces were further fitted to a Hertz model of contact mechanics modified by Sneddon et al. to quantify Young's modulus of elasticity for the cells. Contour plots of the quantified properties described above (i.e., the bacterial surface biopolymer brush length and grafting density, and Young's modulus of elasticity for the cells) based on the location coordinates on the bacterial surfaces were generated. Our contour plots indicated the bacterial cells organize their biopolymers uniquely to help them survive in the environment. Specifically, our results showed that the perimeter of a bacterial cell is characterized by a more flexible as well as longer biopolymer brush compared to those estimated at the center top of the cell. These results suggest that bacteria are likely to use their longer brushes on the edges to facilitate their adhesion by bridging surfaces. Also, they maintain their structural reinforcement by developing higher densities of grafted biopolymers and hence higher elasticities at their centers. Moreover, a stronger linear relationship was observed between the brush thicknesses and the grafting densities for the collapsed brush at the center of the cells when compared to the perimeter of the cells.
在水中对原子力显微镜氮化硅悬臂与大肠杆菌或恶臭假单胞菌的细菌表面生物聚合物之间的作用力进行了空间探测。将这些相互作用拟合到空间排斥模型中，以估计细菌表面生物聚合物刷的长度和接枝密度。进一步将这些力拟合到由斯内登等人修改的接触力学赫兹模型中，以量化细胞的杨氏弹性模量。基于细菌表面上的位置坐标，生成了上述量化特性（即细菌表面生物聚合物刷的长度和接枝密度以及细胞的杨氏弹性模量）的等高线图。我们的等高线图表明，细菌细胞独特地组织其生物聚合物以帮助它们在环境中生存。具体而言，我们的结果表明，与在细胞中心顶部估计的相比，细菌细胞的周边具有更灵活且更长的生物聚合物刷。这些结果表明，细菌可能利用其边缘处更长的刷子通过桥接表面来促进其粘附。此外，它们通过在中心处形成更高密度的接枝生物聚合物并因此具有更高的弹性来维持其结构强化。而且，与细胞周边相比，在细胞中心处塌陷刷子的刷厚度与接枝密度之间观察到更强的线性关系。
