Schär-Zammaretti Prisca, Ubbink Job
Nestlé Research Center, Lausanne, Switzerland.
Biophys J. 2003 Dec;85(6):4076-92. doi: 10.1016/S0006-3495(03)74820-6.
A variety of strains of the genus Lactobacillus was investigated with respect to the structure, softness, and interactions of their outer surface layers in order to construct structure-property relations of the Gram-positive bacterial cell wall. The role of the conformational properties of the constituents of the outer cell-wall layers and their spatial distribution on the cell wall is emphasized. Atomic force microscopy was used to resolve the surface structure, interactions, and softness of the bacterial cell wall at nanometer-length scales and upwards. The pH-dependence of the electrophoretic mobility and a novel interfacial adhesion assay were used to analyze the average physicochemical properties of the bacterial strains. The bacterial surface is smooth when a compact layer of globular proteins constitutes the outer surface, e.g., the S-layer of L. crispatus DSM20584. In contrast, for two other S-layer containing strains (L. helveticus ATCC12046 and L. helveticus ATCC15009), the S-layer is covered by polymeric surface constituents which adopt a much more extended conformation and which confer a certain roughness to the surface. Consequently, the S-layer is important for the overall surface properties of L. crispatus, but not for the surface properties of L. helveticus. Both surface proteins (L. crispatus DSM20584) and (lipo)teichoic acids (L. johnsonii ATCC332) confer hydrophobic properties to the bacterial surface whereas polysaccharides (L. johnsonii DSM20533 and L. johnsonii ATCC 33200) render the bacterial surface hydrophilic. Using the interfacial adhesion assay, it was demonstrated that hydrophobic groups within the cell wall adsorb limited quantities of hydrophobic compounds. The present work demonstrates that the impressive variation in surface properties displayed by even a limited number of genetically-related bacterial strains can be understood in terms of established colloidal concepts, provided that sufficiently detailed structural, chemical, and conformational information on the surface constituents is available.
为构建革兰氏阳性细菌细胞壁的结构-性质关系，对多种乳酸杆菌菌株的外表面层结构、柔软度及其相互作用进行了研究。强调了外细胞壁层成分的构象性质及其在细胞壁上的空间分布的作用。原子力显微镜用于在纳米长度尺度及以上解析细菌细胞壁的表面结构、相互作用和柔软度。利用电泳迁移率的pH依赖性和一种新型界面粘附测定法来分析细菌菌株的平均物理化学性质。当由紧密排列的球状蛋白质层构成外表面时，细菌表面是光滑的，例如卷曲乳杆菌DSM20584的S层。相比之下，对于另外两种含有S层的菌株（瑞士乳杆菌ATCC12046和瑞士乳杆菌ATCC15009），S层被聚合物表面成分覆盖，这些成分采用更为伸展的构象，使表面具有一定粗糙度。因此，S层对卷曲乳杆菌的整体表面性质很重要，但对瑞士乳杆菌的表面性质不重要。表面蛋白（卷曲乳杆菌DSM20584）和（脂）磷壁酸（约氏乳杆菌ATCC332）赋予细菌表面疏水性质，而多糖（约氏乳杆菌DSM20533和约氏乳杆菌ATCC 33200）使细菌表面具有亲水性。通过界面粘附测定法表明，细胞壁内的疏水基团吸附有限量的疏水化合物。目前的工作表明，即使是数量有限的遗传相关细菌菌株所表现出的令人印象深刻的表面性质变化，只要有关于表面成分足够详细的结构、化学和构象信息，就可以用已确立的胶体概念来理解。
