Investigation of biofilms and visualization using non-destructive imaging techniques like X-ray μCT has recently gained interest. Biofilms are congregations of microorganisms that attach to surfaces and comprise of microbial cells embedded in extracellular polymeric substances (EPS). They are ubiquitous entities that are commonly found in any non-sterile setting and have direct implications on human health. Methods to visualize them in-situ are highly needed to understand their behaviour (attachment and detachment) inside a substrate. Contrast-enhanced X-ray μCT is a 3D imaging technique that is capable of visualising objects that have very low attenuation contrast. The use of contrast agents in X-ray μCT has been an evolving process, however, the possible toxic effect of these chemical compounds against biofilms has not been studied in detail. In this study, we focus on the toxic effect of contrast agents and study the diffusion and drainage of contrast agents in biofilms. We propose using water-soluble potassium bromide (KBr) as a suitable contrast agent for enhancement of the attenuation coefficient of a monoculture of Pseudomonas fluorescens biofilms inside a porous substrate. At the given concentration, KBr proved to be less bactericidal compared to other commonly used contrast agents and at 5% w/v concentration we were able to clearly distinguish between the biofilm and the porous substrate.

中文翻译：

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对比剂对多孔基材生物膜的影响及其X射线CT可视化研究

使用非破坏性成像技术（如 X 射线 μCT）对生物膜和可视化的研究最近引起了人们的兴趣。生物膜是附着在表面的微生物的聚集体，由嵌入细胞外聚合物 (EPS) 的微生物细胞组成。它们是无处不在的实体，在任何非无菌环境中都普遍存在，对人类健康有直接影响。非常需要在原位可视化它们的方法，以了解它们在基板内的行为（附着和分离）。对比增强 X 射线 μCT 是一种 3D 成像技术，能够对衰减对比度非常低的物体进行可视化。在 X 射线 μCT 中使用造影剂是一个不断发展的过程，但是，尚未详细研究这些化合物对生物膜的可能毒性作用。在这项研究中，我们专注于造影剂的毒性作用，并研究造影剂在生物膜中的扩散和引流。我们建议使用水溶性溴化钾 (KBr) 作为合适的造影剂，以增强多孔基质内荧光假单胞菌生物膜的单一培养的衰减系数。在给定的浓度下，与其他常用造影剂相比，KBr 的杀菌力较低，并且在 5% w/v 浓度下，我们能够清楚地区分生物膜和多孔基材。我们建议使用水溶性溴化钾 (KBr) 作为合适的造影剂，以增强多孔基质内荧光假单胞菌生物膜的单一培养的衰减系数。在给定的浓度下，与其他常用造影剂相比，KBr 的杀菌力较低，并且在 5% w/v 浓度下，我们能够清楚地区分生物膜和多孔基材。我们建议使用水溶性溴化钾 (KBr) 作为合适的造影剂，以增强多孔基质内荧光假单胞菌生物膜的单一培养的衰减系数。在给定的浓度下，与其他常用造影剂相比，KBr 的杀菌力较低，并且在 5% w/v 浓度下，我们能够清楚地区分生物膜和多孔基材。