Biofilm formation by bacteria protects them against environmental stresses such as desiccation, shear forces and antimicrobial agents, making them much harder to remove and increasing their virulence and persistence in industrial water systems and biomedical equipment. One promising method of disrupting biofilm formation and growth is to employ passive surface structures to inhibit bacterial adhesion and aggregation. However, most studies thus far have mainly focused on the early stages of biofilm formation and it is unclear if the influence of surface topography in the early phase will propagate to later stages. Here, we attempt to address this with an investigation into the biofilm formation of Pseudomonas aeruginosa on 25 different nanograting geometries, with dimensions that were systematically varied from subcellular to cellular sizes. The biofilms were characterized from the exponential growth phase to the decline phase, in intervals of 24 H over 4 days, using confocal scanning laser microscopy. Comparing the maximum volume of biofilm formed on each surface over 96 H, it was found that approximately 1/3 of the nanograting geometries exhibited 72 ± 16 % lower biovolume density than a flat surface. Bacteria on these nanogratings were also observed to form 40 ± 11 % smaller microcolonies that were 17 ± 6 % less compact than that found on the control surface. The majority of these nanogratings had deep trenches ( i.e. depth ≥ 70% of the cell diameter). Furthermore, P. aeruginosa cells were observed to multiply at approximately twice the rate on almost all the nanogratings compared to flat surfaces, but these cell populations also began to decline 24 H earlier than those on a flat surface. Using available literature on P. aeruginosa , a qualitative model was put forth, attributing the results to increased cell motility, decreased exopolysaccharide formation and disrupted psl adhesin/signal trails on nanogratings. These factors, together, led to the net effects of reduced attachment, increased scattering of cells and rapid decline of the biofilms on nanogratings. The insights derived from this study suggest that passive surface geometries can be designed and optimized to successfully control/inhibit biofilm formation and growth.

中文翻译：

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亚细胞纳米光栅几何形状对细菌生物膜形成和生长的影响。

细菌形成的生物膜可保护它们免受干燥，剪切力和抗菌剂等环境压力的影响，使其更难去除，并提高其在工业用水系统和生物医学设备中的毒力和持久性。破坏生物膜形成和生长的一种有前途的方法是采用被动表面结构来抑制细菌粘附和聚集。但是，迄今为止，大多数研究主要集中在生物膜形成的早期阶段，尚不清楚表面形貌在早期阶段的影响是否会传播到后期阶段。在这里，我们试图通过调查生物膜的生物膜形成来解决这个问题。铜绿假单胞菌在25种不同的纳米光栅几何形状上，尺寸从亚细胞到细胞大小都有系统地变化。使用共聚焦扫描激光显微镜对生物膜从指数生长期到衰退期进行了表征，间隔为4天，时间为24H。比较在96 H以上每个表面上形成的生物膜的最大体积，发现大约1/3的纳米光栅几何形状的生物体积密度比平坦表面低72±16％。还观察到在这些纳米光栅上的细菌形成的微菌落小40±11％，其致密性比对照表面小17±6％。这些纳米光栅大多数具有深沟槽（ 即深度≥孔直径的70％）。此外，铜绿假单胞菌与平坦表面相比，观察到的细胞在几乎所有纳米光栅上的增殖速率约为其两倍，但这些细胞群体也比平坦表面上的细胞提前24 H下降。使用以下文献铜绿假单胞菌 ，提出了定性模型，将结果归因于细胞运动性增加，胞外多糖形成减少和破坏 psl纳米光栅上的粘附素/信号路径。这些因素共同导致了减少附着力，增加细胞散布以及纳米光栅上生物膜迅速下降的净效应。这项研究得出的见解表明，可以设计和优化被动表面的几何形状，以成功地控制/抑制生物膜的形成和生长。