Han Rui, Feng Xi-Qiao, Vollmer Waldemar, Stoodley Paul, Chen Jinju
School of Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, UK.
Institute of Biomechanics and Medical Engineering, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
J Colloid Interface Sci. 2023 Jun 15;640:510-520. doi: 10.1016/j.jcis.2023.02.100. Epub 2023 Feb 23.
Bacteria adapt the mechanical properties of their cell envelope, including cell wall stiffness, turgor, and cell wall tension and deformation, to grow and survive in harsh environments. However, it remains a technical challenge to simultaneously determine these mechanical properties at a single cell level. Here we combined theoretical modelling with an experimental approach to quantify the mechanical properties and turgor of Staphylococcus epidermidis. It was found that high osmolarity leads to a decrease in both cell wall stiffness and turgor. We also demonstrated that the turgor change is associated with a change in the viscosity of the bacterial cell. We predicted that the cell wall tension is much higher in deionized (DI) water and it decreases with an increase in osmolality. We also found that an external force increases the cell wall deformation to reinforce its adherence to a surface and this effect can be more significant in lower osmolarity. Overall, our work highlights how bacterial mechanics supports survival in harsh environments and uncovers the adaption of bacterial cell wall mechanical integrity and turgor to osmotic and mechanical challenges.
细菌会调整其细胞壁的力学特性，包括细胞壁硬度、膨压以及细胞壁张力和变形，以便在恶劣环境中生长和存活。然而，在单细胞水平上同时测定这些力学特性仍然是一项技术挑战。在此，我们将理论建模与实验方法相结合，以量化表皮葡萄球菌的力学特性和膨压。研究发现，高渗透压会导致细胞壁硬度和膨压均降低。我们还证明，膨压变化与细菌细胞粘度的变化有关。我们预测，在去离子水中细胞壁张力要高得多，并且它会随着渗透压摩尔浓度的增加而降低。我们还发现，外力会增加细胞壁变形，以增强其对表面的附着力，并且这种效应在较低渗透压下可能更显著。总体而言，我们的工作突出了细菌力学如何支持在恶劣环境中的生存，并揭示了细菌细胞壁机械完整性和膨压对渗透和机械挑战的适应性。
