A Dual Rheometer-Microscope Instrument for the Quantitative Characterization of Bacterial Biofilms

目前估计，地球上80%的细菌生活在生物膜内的群落中，生物膜是一种由胞外多糖、DNA、蛋白质和各种小分子组成的介质。生物膜是一种机械坚固的材料，它包围并保护细菌免受外部世界的影响。因此，这些细菌通常对抗生素和消毒剂更具抗性或耐受性。生物膜在医疗器械上的发展，如导管和植入物，以及在活组织中，现在提出了一些重要的问题，因为用抗生素进行的密集和长期治疗仍然经常导致治疗失败，以及更高的发病率和死亡率-这是一个世界性的问题，仍然需要开发有效的解决方案。生物膜也具有有用的特性，例如在水和废水处理工艺的开发中。生物膜絮凝物允许细菌悬浮在培养基中，或者它们附着在惰性载体上，生物质在惰性载体上生长。因此，了解和控制生物膜的特性在这些研究领域中至关重要。最近，界面和本体流变学已被引入作为定量监测细菌生物膜的粘弹性性质的技术，这与膜的稳定性直接相关。我们在本提案中要求的商业流变仪将配备界面几何结构，沿着其他各种体积测量几何结构，这将允许时间分辨的定量测量生物膜的粘弹性，荧光显微镜允许微观结构和组成分析。以前的工作已经证明，这种技术是特别敏感的生物膜的组成，这可以通过基因敲除和外部环境控制-温度，介质的组成等，因为时间分辨的测量将是可能的，量化扰动的影响，如添加抗生素，生物膜的粘弹性，微观结构和组成特性将是可能的。最后，在生物安全2级实验室中安装流变仪将允许研究沙门氏菌等病理菌株-这是加拿大的独特配置。这个原始的多学科项目是七个共同申请人和四个合作者之间的首次合作，他们具有互补的专业知识，包括流变学，细菌微生物学，界面科学，水/废水处理工艺，兽医和儿科学，来自蒙特利尔理工大学，蒙特利尔大学，INRS研究所Armand-Frappier和斯坦福大学。

It is currently estimated that 80% of the planet's bacteria live in communities inside biofilms - a medium comprised of exopolysaccharides, DNA, proteins and various small molecules. A biofilm is a mechanically robust material that surrounds and protects the bacteria from the external world. As a result, these bacteria are generally more resistant or tolerant to antibiotics and disinfectants. The development of biofilms on medical devices, such as catheter and implants, and in living tissues, now poses some important issues, since intensive and prolonged treatments with antibiotics still often lead to treatment failure, and higher morbidity and mortality rates - this is a worldwide issue that still needs the development of efficient solutions. Biofilms also have useful properties, for example in the development of treatment processes for water and wastewater. Biofilm flocs allow the suspension of bacteria in the medium, or their adherence to inert supports onto which the biomass develops. As a result, understanding and controlling the properties of biofilms is of critical importance in these areas of research. Very recently, both interfacial and bulk rheology have been introduced as techniques to monitor quantitatively the viscoelastic properties of bacterial biofilms, which are directly related to the stability of the film. The commercial rheometer that we request in this proposal will be equipped with interfacial geometries, along with other various bulk measurement geometries, that will allow time-resolved, quantitative measurements of biofilms' viscoelastic properties, with a fluorescence microscope allowing microstructure and composition analyses. Previous work has demonstrated that this technique is particularly sensitive to biofilm composition, which can be controlled by gene knockout and by the external environment - temperature, composition of the media, etc. Since time-resolved measurements will be possible, quantifying the effects of perturbations, such as the addition of antibiotics, on the viscoelastic, microstructural and composition properties of biofilms will be possible. Finally, the installation of the rheometer in a Biosafety level 2 laboratory will allow the study of pathological strains such as Salmonella - a unique configuration in Canada. This original multidisciplinary program is a first collaboration between seven co-applicants and 4 collaborators with complementary expertises, including rheology, bacterial microbiology, interfacial science, water/wastewater treatment processes, veterinary medecine, and pediatrics, from Polytechnique Montreal, Université de Montréal, INRS Institut Armand-Frappier, and Stanford University.