Probiotic strains from the Bifidobacterium or Lactobacillus genera improve health outcomes in models of metabolic and cardiovascular disease. Yet, underlying mechanisms governing these improved health outcomes are rooted in the interaction of gut microbiota, intestinal interface, and probiotic strain. Central to defining the underlying mechanisms governing these improved health outcomes is the development of adaptable and non-invasive tools to study probiotic localization and colonization within the host gut microbiome. The objective of this study was to test labeling and tracking efficacy of Bifidobacterium animalis subspecies lactis 420 (B420) using a common clinical imaging agent, indocyanine green (ICG). ICG was an effective in situ labeling agent visualized in either intact mouse or excised gastrointestinal (GI) tract at different time intervals. Quantitative PCR was used to validate ICG visualization of B420, which also demonstrated that B420 transit time matched normal murine GI motility (~8 hours). Contrary to previous thoughts, B420 did not colonize any region of the GI tract whether following a single bolus or daily administration for up to 10 days. We conclude that ICG may provide a useful tool to visualize and track probiotic species such as B420 without implementing complex molecular and genetic tools. Proof-of-concept studies indicate that B420 did not colonize and establish residency align the murine GI tract.

双歧杆菌属或乳杆菌属的益生菌菌株可改善代谢和心血管疾病模型的健康结果。然而，控制这些改善的健康结果的潜在机制植根于肠道微生物群、肠道界面和益生菌菌株的相互作用。定义控制这些改善的健康结果的基本机制的核心是开发适应性强的非侵入性工具来研究益生菌在宿主肠道微生物组内的定位和定殖。本研究的目的是使用常见的临床显像剂吲哚菁绿 (ICG)测试动物双歧杆菌乳亚种420 (B420) 的标记和追踪功效。ICG 是一种有效的原位标记剂，可在完整小鼠或切除的胃肠道 (GI) 中以不同的时间间隔进行可视化。使用定量 PCR 验证 B420 的 ICG 可视化，这也证明 B420 转运时间与正常小鼠胃肠道运动（约 8 小时）相匹配。与之前的想法相反，无论是单次推注还是每日给药长达 10 天，B420 都不会在胃肠道的任何区域定植。我们的结论是，ICG 可以提供一种有用的工具来可视化和跟踪 B420 等益生菌物种，而无需使用复杂的分子和遗传工具。概念验证研究表明，B420 并未在小鼠胃肠道中定殖并建立驻留。