Departamento de Física Aplicada, Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil.
PLoS One. 2013 Sep 20;8(9):e75247. doi: 10.1371/journal.pone.0075247. eCollection 2013.
The phytopathogen Xylella fastidiosa grows as a biofilm causing vascular occlusion and consequently nutrient and water stress in different plant hosts by adhesion on xylem vessel surfaces composed of cellulose, hemicellulose, pectin and proteins. Understanding the factors which influence bacterial adhesion and biofilm development is a key issue in identifying mechanisms for preventing biofilm formation in infected plants. In this study, we show that X. fastidiosa biofilm development and architecture correlate well with physicochemical surface properties after interaction with the culture medium. Different biotic and abiotic substrates such as silicon (Si) and derivatized cellulose films were studied. Both biofilms and substrates were characterized at the micro- and nanoscale, which corresponds to the actual bacterial cell and membrane/ protein length scales, respectively. Our experimental results clearly indicate that the presence of surfaces with different chemical composition affect X. fastidiosa behavior from the point of view of gene expression and adhesion functionality. Bacterial adhesion is facilitated on more hydrophilic surfaces with higher surface potentials; XadA1 adhesin reveals different strengths of interaction on these surfaces. Nonetheless, despite different architectural biofilm geometries and rates of development, the colonization process occurs on all investigated surfaces. Our results univocally support the hypothesis that different adhesion mechanisms are active along the biofilm life cycle representing an adaptation mechanism for variations on the specific xylem vessel composition, which the bacterium encounters within the infected plant.
植物病原菌 Xylella fastidiosa 以生物膜的形式生长，通过黏附在由纤维素、半纤维素、果胶和蛋白质组成的木质部导管表面，导致不同植物宿主的血管阻塞，进而导致营养和水分胁迫。了解影响细菌黏附和生物膜形成的因素是识别防止感染植物生物膜形成机制的关键问题。在这项研究中，我们表明 X. fastidiosa 生物膜的形成和结构与与培养基相互作用后的理化表面特性密切相关。研究了不同的生物和非生物底物，如硅 (Si) 和衍生纤维素膜。对生物膜和底物进行了微观和纳米尺度的表征，分别对应于实际细菌细胞和膜/蛋白质长度尺度。我们的实验结果清楚地表明，具有不同化学成分的表面的存在会影响 X. fastidiosa 从基因表达和黏附功能的角度来看的行为。在更亲水的表面上，具有更高表面电位的表面有利于细菌黏附；XadA1 黏附素在这些表面上表现出不同的相互作用强度。尽管生物膜的几何形状和发育速度不同，但在所有研究的表面上都发生了定植过程。我们的结果明确支持这样一种假设，即在生物膜生命周期中存在不同的黏附机制，这是一种适应机制，可针对细菌在感染植物中遇到的特定木质部导管组成的变化。
