宁波大学康雪团队利用固体核磁共振光谱技术，揭示了枯草芽孢杆菌生物膜的分子组成和结构。相关研究成果发表在2024年4月17日出版的国际知名学术期刊《美国化学会杂志》。

生物膜复杂而动态的组成，以及其复杂的结构组装机制，赋予了它们在不同条件下茁壮成长的非凡能力，而这些条件通常对单个细胞不利。由于生物膜的内在复杂性和非侵入性技术的有限可用性，对其天然状态下的生物膜进行表征具有重大挑战性。

该文中，研究人员利用固态核磁共振（NMR）光谱对枯草芽孢杆菌的生物膜进行了深入分析。数据揭示了生物膜内一个动态的独特组织：一个占主导地位的亲水性和可移动的框架，中间穿插着水可及性有限的小而刚性的核心。在这些异质刚性芯中，主要部件在很大程度上是自组装的。TasA纤维是最坚固的元素，进一步为细胞聚集体和一些脂质囊泡提供一定程度的机械支持。

值得注意的是，即使没有主要的细胞外聚合物（EPS）聚合物，刚性细胞聚集体也可以持续存在，尽管这会导致它们的刚性和水可及性略有变化。胞外多糖仅存在于可移动结构域中，在其保水性能中发挥着关键作用。具体而言，所有的水分子都紧密结合在生物膜基质中。这些发现揭示了生物膜中的双层防御策略：通过流动相中有限的水流动性形成的扩散屏障，和通过刚性相中有限的可及性形成的物理屏障。

作为对这些发现的补充，研究人员全面的原位成分分析不仅对描述复杂的生物膜结构至关重要，而且揭示了在已知途径之外合成胞外多糖的替代遗传机制的存在。

附：英文原文

Title: Uncovering the Molecular Composition and Architecture of the Bacillus subtilis Biofilm via Solid-State NMR Spectroscopy

Author: Yi Xue, Chenjie Yu, Han Ouyang, Jiaofang Huang, Xue Kang

Issue&Volume: April 17, 2024

Abstract: The complex and dynamic compositions of biofilms, along with their sophisticated structural assembly mechanisms, endow them with exceptional capabilities to thrive in diverse conditions that are typically unfavorable for individual cells. Characterizing biofilms in their native state is significantly challenging due to their intrinsic complexities and the limited availability of noninvasive techniques. Here, we utilized solid-state nuclear magnetic resonance (NMR) spectroscopy to analyze Bacillus subtilis biofilms in-depth. Our data uncover a dynamically distinct organization within the biofilm: a dominant, hydrophilic, and mobile framework interspersed with minor, rigid cores of limited water accessibility. In these heterogeneous rigid cores, the major components are largely self-assembled. TasA fibers, the most robust elements, further provide a degree of mechanical support for the cell aggregates and some lipid vesicles. Notably, rigid cell aggregates can persist even without the major extracellular polymeric substance (EPS) polymers, although this leads to slight variations in their rigidity and water accessibility. Exopolysaccharides are exclusively present in the mobile domain, playing a pivotal role in its water retention property. Specifically, all water molecules are tightly bound within the biofilm matrix. These findings reveal a dual-layered defensive strategy within the biofilm: a diffusion barrier through limited water mobility in the mobile phase and a physical barrier posed by limited water accessibility in the rigid phase. Complementing these discoveries, our comprehensive, in situ compositional analysis is not only essential for delineating the sophisticated biofilm architecture but also reveals the presence of alternative genetic mechanisms for synthesizing exopolysaccharides beyond the known pathway.

DOI: 10.1021/jacs.4c00889

Source: https://pubs.acs.org/doi/full/10.1021/jacs.4c00889