Li Alex G, Burggraf Larry W, Xing Yun
Department of Engineering Physics, Air Force Institute of Technology, Wright-Patterson Air Force Base, Ohio, USA
Department of Engineering Physics, Air Force Institute of Technology, Wright-Patterson Air Force Base, Ohio, USA.
Appl Environ Microbiol. 2016 May 2;82(10):2988-2999. doi: 10.1128/AEM.00431-16. Print 2016 May 15.
The study of structures and properties of bacterial spores is important to understanding spore formation and biological responses to environmental stresses. While significant progress has been made over the years in elucidating the multilayer architecture of spores, the mechanical properties of the spore interior are not known. Here, we present a thermal atomic force microscopy (AFM) study of the nanomechanical properties of internal structures of Bacillus anthracis spores. We developed a nanosurgical sectioning method in which a stiff diamond AFM tip was used to cut an individual spore, exposing its internal structure, and a soft AFM tip was used to image and characterize the spore interior on the nanometer scale. We observed that the elastic modulus and adhesion force, including their thermal responses at elevated temperatures, varied significantly in different regions of the spore section. Our AFM images indicated that the peptidoglycan (PG) cortex of Bacillus anthracis spores consisted of rod-like nanometer-sized structures that are oriented in the direction perpendicular to the spore surface. Our findings may shed light on the spore architecture and properties.
A nanosurgical AFM method was developed that can be used to probe the structure and properties of the spore interior. The previously unknown ultrastructure of the PG cortex of Bacillus anthracis spores was observed to consist of nanometer-sized rod-like structures that are oriented in the direction perpendicular to the spore surface. The variations in the nanomechanical properties of the spore section were largely correlated with its chemical composition. Different components of the spore materials showed different thermal responses at elevated temperatures.
对细菌芽孢的结构和特性进行研究，对于理解芽孢形成以及生物体对环境压力的反应具有重要意义。尽管多年来在阐明芽孢的多层结构方面已取得显著进展，但芽孢内部的力学特性仍不清楚。在此，我们展示了一项利用热原子力显微镜（AFM）对炭疽芽孢杆菌芽孢内部结构的纳米力学特性进行的研究。我们开发了一种纳米手术切片方法，其中使用坚硬的金刚石AFM探针切割单个芽孢，以暴露其内部结构，并用柔软的AFM探针在纳米尺度上对芽孢内部进行成像和表征。我们观察到，弹性模量和粘附力，包括它们在高温下的热响应，在芽孢切片的不同区域有显著变化。我们的AFM图像表明，炭疽芽孢杆菌芽孢的肽聚糖（PG）皮层由纳米级的棒状结构组成，这些结构沿垂直于芽孢表面的方向排列。我们的发现可能有助于揭示芽孢的结构和特性。
开发了一种纳米手术AFM方法，可用于探测芽孢内部的结构和特性。观察到炭疽芽孢杆菌芽孢PG皮层以前未知的超微结构由纳米级的棒状结构组成，这些结构沿垂直于芽孢表面的方向排列。芽孢切片纳米力学特性的变化与其化学成分在很大程度上相关。芽孢材料的不同组分在高温下表现出不同的热响应。
