Characterising bacterial biofilm growth in porous media is important for developing reliable numerical models of biofouling in industrial biofilters. One of the promising imaging methods to do that has been a recent successful application of X-ray microtomography. However, this technique requires a contrast agent (1-chloronaphtalene, for example) to distinguish biofilm from the liquid phase, which raises concern about biofilm disruption and impaired image interpretation. To overcome these drawbacks, we tested a new approach based on neutron tomography (NT), which does not need a contrast agent, by imaging two types of porous media (polytetrafluoroethylene – PTFE – and clay beads of various diameters) in glass or PTFE tubes in which bacterial biofilms were grown for 7 days and by comparing these images with the ones obtained with X-ray microtomography. NT images showed that the biofilm formed preferentially around the beads and at bead/bead interface. Visual comparison of both imaging techniques showed consistent biofilm spatial distributions and that the contrasting agent did not significantly disrupt the biofilm. NT images, on the other hand, were still too noisy to allow quantitative measurements. Therefore, X-ray microtomography (provided it uses non-disruptive contrast agents) seems to provide more reliable microstructural descriptors.

中文翻译：

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首次使用中子显微断层成像技术在 3D 多孔介质中可视化细菌生物膜，无需造影剂

表征多孔介质中的细菌生物膜生长对于开发工业生物过滤器中生物污垢的可靠数值模型非常重要。有希望的成像方法之一是最近成功应用 X 射线显微断层摄影术。然而，该技术需要造影剂（例如 1-氯萘）来区分生物膜和液相，这引起了人们对生物膜破坏和图像解释受损的担忧。为了克服这些缺点，我们测试了一种基于中子断层扫描 (NT) 的新方法，它不需要造影剂，通过在细菌生物膜生长 7 天的玻璃或 PTFE 管中对两种类型的多孔介质（聚四氟乙烯 – PTFE – 和各种直径的粘土珠）进行成像，并将这些图像与 X 射线显微断层扫描获得的图像进行比较。NT 图像显示生物膜优先在珠子周围和珠子/珠子界面处形成。两种成像技术的视觉比较显示一致的生物膜空间分布，并且造影剂没有显着破坏生物膜。另一方面，NT 图像仍然过于嘈杂，无法进行定量测量。因此，X 射线显微断层扫描（如果它使用非破坏性造影剂）似乎提供了更可靠的微观结构描述符。NT 图像显示生物膜优先在珠子周围和珠子/珠子界面处形成。两种成像技术的视觉比较显示一致的生物膜空间分布，并且造影剂没有显着破坏生物膜。另一方面，NT 图像仍然过于嘈杂，无法进行定量测量。因此，X 射线显微断层扫描（如果它使用非破坏性造影剂）似乎提供了更可靠的微观结构描述符。NT 图像显示生物膜优先在珠子周围和珠子/珠子界面处形成。两种成像技术的视觉比较显示一致的生物膜空间分布，并且造影剂没有显着破坏生物膜。另一方面，NT 图像仍然过于嘈杂，无法进行定量测量。因此，X 射线显微断层扫描（如果它使用非破坏性造影剂）似乎提供了更可靠的微观结构描述符。