The biofilm chemical and physical properties in engineered systems play an important role in governing pathogen transmission, fouling facilities, and corroding metal surfaces. Here, we investigated how simulated drinking water biofilm chemical composition, structure, and stiffness responded to the common scale control practice of adjusting divalent ions and adding polyphosphate. Magnetomotive optical coherence elastography (MM-OCE), a tool developed for diagnosing diseased tissues, was used to determine biofilm stiffness in this study. MM-OCE, together with atomic force microscopy (AFM), revealed that the biofilms developed from a drinking water source with high divalent ions were stiffer compared to biofilms developed either from the drinking water source with low divalent ions or the water containing a scale inhibitor (a polyphosphate). The higher stiffness of biofilms developed from the water containing high divalent ions was attributed to the high content of calcium carbonate, suggested by biofilm composition examination. In addition, by examining the biofilm structure using optical coherence tomography (OCT), the highest biofilm thickness was found for biofilms developed from the water containing the polyphosphate. Compared to the stiff biofilms developed from the water containing high divalent ions, the soft and thick biofilms developed from the water containing polyphosphate will be expected to have higher detachment under drinking water flow. This study suggested that water chemistry could be used to predict the biofilm properties and subsequently design the microbial safety control strategies.

工程系统中的生物膜化学和物理性质在控制病原体传播，结垢设施和腐蚀金属表面方面起着重要作用。在这里，我们研究了模拟的饮用水中生物膜的化学成分，结构和硬度如何响应调节二价离子和添加多磷酸盐的常见垢控制实践。磁动力光学相干弹性成像（MM-OCE），一种用于诊断患病组织的工具，用于确定生物膜的硬度。MM-OCE与原子力显微镜（AFM）一起显示，与高二价离子饮用水源或含有阻垢剂的水相比，由高二价离子饮用水源产生的生物膜更坚硬。 （一种多磷酸盐）。由生物膜组成检查表明，从含有高二价离子的水中形成的生物膜具有较高的刚度，这归因于碳酸钙的含量高。此外，通过使用光学相干断层扫描（OCT）检查生物膜结构，发现从含多磷酸盐的水中形成的生物膜具有最高的生物膜厚度。与由含高二价离子的水形成的坚硬生物膜相比，由含聚磷酸盐的水形成的软而厚的生物膜在饮用水流下有望具有更高的分离性。这项研究表明，水化学可用于预测生物膜特性，并随后设计微生物安全控制策略。