Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin 10115, Germany.
Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin 10115, Germany
Open Biol. 2018 Aug;8(8). doi: 10.1098/rsob.180066.
Bacterial biofilms are large aggregates of cells embedded in an extracellular matrix of self-produced polymers. In macrocolony biofilms of , this matrix is generated in the upper biofilm layer only and shows a surprisingly complex supracellular architecture. Stratified matrix production follows the vertical nutrient gradient and requires the stationary phase (RpoS) subunit of RNA polymerase and the second messenger c-di-GMP. By visualizing global gene expression patterns with a newly designed fingerprint set of Gfp reporter fusions, our study reveals the spatial order of differential sigma factor activities, stringent control of ribosomal gene expression and c-di-GMP signalling in vertically cryosectioned macrocolony biofilms. Long-range physiological stratification shows a duplication of the growth-to-stationary phase pattern that integrates nutrient and oxygen gradients. In addition, distinct short-range heterogeneity occurs within specific biofilm strata and correlates with visually different zones of the refined matrix architecture. These results introduce a new conceptual framework for the control of biofilm formation and demonstrate that the intriguing extracellular matrix architecture, which determines the emergent physiological and biomechanical properties of biofilms, results from the spatial interplay of global gene regulation and microenvironmental conditions. Overall, mature bacterial macrocolony biofilms thus resemble the highly organized tissues of multicellular organisms.
细菌生物膜是由细胞组成的大型聚集体，嵌入在由自身产生的聚合物组成的细胞外基质中。在 的宏观菌落生物膜中，这种基质仅在上层生物膜层中产生，并显示出惊人复杂的超细胞结构。分层基质的产生遵循垂直营养梯度，需要 RNA 聚合酶的静止期（RpoS）亚基和第二信使 c-di-GMP。通过使用新设计的 GFP 报告基因融合指纹集可视化全局基因表达模式，我们的研究揭示了垂直冷冻切片宏观菌落生物膜中差异 σ 因子活性、核糖体基因表达严格控制和 c-di-GMP 信号转导的空间顺序。长程生理分层显示出生长到静止期模式的重复，该模式整合了营养和氧气梯度。此外，在特定生物膜层内会出现明显的短程异质性，并与细化基质结构的视觉不同区域相关。这些结果为生物膜形成的控制引入了一个新概念框架，并表明决定生物膜出现的生理和生物力学特性的迷人细胞外基质结构是由全局基因调控和微环境条件的空间相互作用产生的。总的来说，成熟的细菌宏观菌落生物膜类似于多细胞生物的高度组织化组织。
