Restroom Microbiome Succession Study

The indoor environment is the dominant ecosystem for the majority of industrialized humanity and is unlike any biome previously experienced by our species. Bacteria commonly associated with our bodies dominate the Built Environment (BE). Using a unique ecosystem model - a public restroom - we show that surface-associated microbial communities follow a predictable ecological succession, from a community dominated by fecal microbiota to one dominated by skin and ‘outdoor’ microbiota. We analyzed microbial communities following decontamination of floors, toilet seats, and soap dispensers in 4 public restrooms hourly, daily, and weekly. Only toilet seat communities showed differentiation based on gender, with Lactobacillus dominating female seats and Roseburia and Blautia more prevalent on male seats. On floors, a late successional community developed quickly, and showed remarkably stability over weeks to months. Despite late-successional dominance by skin- and outdoor-associated microbiota, the core microbiome was composed almost exclusively of human gut bacteria, suggesting that a relatively homogenous pool of abundant fecal microbes is continuously dispersed to all floor surfaces. OTU abundances were not significantly correlated with measured physical parameters. Together, these data indicate that human-associated microbes dominate restroom surfaces and follow neutral community assembly. We suggest that BE surface environments are microbial ‘deserts’, where resources are scarce and persistence depends upon dormancy or continuous dispersal, and we show that overzealous cleaning regimes in public restrooms lead to a transient dominance of human fecal microbiota, while normal soap and water cleaning results in a stable community dominated by skin-associated microbes.

室内环境是绝大多数工业化人类所处的主导生态系统，其与人类此前经历过的任何生物群系均截然不同。与人体紧密关联的细菌在建筑环境（Built Environment, BE）中占据绝对主导地位。本研究以公共卫生间作为独特的生态系统模型，证实表面附着的微生物群落遵循可预测的生态演替规律：群落结构从最初以粪便微生物群为主导，逐步转变为以皮肤微生物群与「户外」微生物群为主导的状态。我们对4间公共卫生间的地面、马桶座圈及皂液器完成消毒净化后，按小时、每日及每周的频次对其表面微生物群落开展分析。仅马桶座圈的微生物群落呈现出基于性别的分化特征：乳杆菌属（Lactobacillus）在女性使用者接触的座圈上占主导地位，而罗斯氏菌属（Roseburia）与布劳特氏菌属（Blautia）在男性座圈上的相对丰度更高。在地面表面，演替后期的微生物群落快速形成，并在数周至数月的周期内表现出极强的稳定性。尽管演替后期的群落以皮肤及户外相关微生物群为主，但核心微生物组几乎完全由人类肠道细菌构成，这表明大量粪便微生物形成了相对均一的微生物储库，并持续扩散至所有地面表面。操作分类单元（Operational Taxonomic Unit, OTU）的丰度与实测得到的物理参数无显著相关性。综合上述实验数据，本研究表明与人类相关的微生物主导了公共卫生间的表面群落，并遵循中性群落组装规律。我们提出，建筑环境的表面属于微生物「荒漠」——其可利用资源稀缺，微生物的存续依赖于休眠状态或持续的微生物扩散；同时本研究证实，公共卫生间内过度严苛的清洁方案会导致人类粪便微生物群短暂占据优势，而常规的皂液水洗清洁则会形成以皮肤相关微生物为主的稳定群落。