Toward Meta-Omics Governance of the Urban Microbiome Commons.

Urban microbial communities are undergoing directional homogenization across soils, wildlife gut microbiota, and human exposure pathways, yet no monitoring framework exists to track this loss or govern the probiotic city interventions now scaling without ecological oversight. I argue that the urban microbiome constitutes an "invisible commons": a shared, depletable resource whose depletion goes unaccounted for because it has never been made measurable. The meta-omics community has the tools to change this. I propose five monitoring priorities and six immediately deployable indicators and show that the governance architecture required to convert these measurements into decisions already exists in conservation biology. What is missing is not new science but the decision to apply existing methods to this domain. With antibiotic resistance causing over one million deaths annually and probiotic city interventions advancing without resistance gene screening, that decision is overdue.