Molecular Imaging North Competence Center, Section Biomedical Imaging, Department of Radiology and Neuroradiology, University Hospital Schleswig-Holstein, Am Botanischen Garten 14, 24118, Kiel, Germany.
Department of Food and Environmental Sciences, University of Helsinki, Viikinkaari 9, 00014, Helsinki, Finland.
BMC Microbiol. 2019 Jul 18;19(1):167. doi: 10.1186/s12866-019-1538-z.
The human gastrointestinal (GI) tract microbiota has been a subject of intense research throughout the 3rd Millennium. Now that a general picture about microbiota composition in health and disease is emerging, questions about factors determining development of microbiotas with specific community structures will be addressed. To this end, usage of murine models for colonization studies remains crucial. Optical in vivo imaging of either bioluminescent or fluorescent bacteria is the basis for non-invasive detection of intestinal colonization of bacteria. Although recent advances in in vivo fluorescence imaging have overcome many limitations encountered in bioluminescent imaging of intestinal bacteria, such as requirement for live cells, high signal attenuation and 2D imaging, the method is still restricted to bacteria for which molecular cloning tools are available.
Here, we present usage of a lipophilic fluorescent dye together with Katushka far-red fluorescent protein to establish a dual-color in vivo imaging system to monitor GI transit of different bacterial strains, suitable also for strains resistant to genetic labeling. Using this system, we were able to distinguish two different E. coli strains simultaneously and show their unique transit patterns. Combined with fluorescence molecular tomography, these distinct strains could be spatially and temporally resolved and quantified in 3D.
Developed novel method for labeling microbes and identify their passage both temporally and spatially in vivo makes now possible to monitor all culturable bacterial strains, also those that are resistant to conventional genetic labeling.
人类胃肠道（GI）微生物群一直是第三个千年中研究的热点。现在，关于健康和疾病中微生物群组成的总体情况正在出现，关于决定具有特定群落结构的微生物群发展的因素的问题将得到解决。为此，使用用于定植研究的啮齿动物模型仍然至关重要。对生物发光或荧光细菌进行光学体内成像，是对细菌肠道定植进行非侵入性检测的基础。尽管体内荧光成像的最新进展克服了肠道细菌生物发光成像中遇到的许多限制，例如对活细胞的要求、信号衰减高和二维成像，但该方法仍然仅限于可使用分子克隆工具的细菌。
在这里，我们提出了使用亲脂性荧光染料和 Katushka 远红荧光蛋白建立双色体内成像系统来监测不同细菌菌株的 GI 转运，该系统也适用于对遗传标记有抗性的菌株。使用该系统，我们能够同时区分两种不同的大肠杆菌菌株，并显示它们独特的转运模式。结合荧光分子断层扫描，可以在 3D 中对这些不同的菌株进行空间和时间分辨和定量。
开发了一种标记微生物并在体内同时进行时间和空间识别其通过的新方法，使得现在可以监测所有可培养的细菌菌株，包括那些对传统遗传标记有抗性的菌株。
