The linkage between microbial community dynamics and urbanization age

Urbanization exerts unprecedented pressure on the microbial community, with far-reaching implications for human health. While previous studies have documented microbial variations across the geographic urban–rural gradient, the temporal dynamics of microbial communities in response to urbanization remain poorly understood. Leveraging global datasets of 2,110 metagenomes spanning 45 cities on 6 continents and annual artificial impervious surface data (1985–2018), we investigated how microbial composition, diversity and functions correlate with urbanization age. Our results reveal that, with increasing urbanization age, there is a significant decline in microbial alpha diversity (P < 0.05), a pronounced compositional shift from nature-associated to human-associated microorganisms (P < 0.001), a rise in the total relative abundance of opportunistic human pathogens (P < 0.05) and a functional restructuring with potential human health implications. These findings provide empirical evidence of microbial community dynamics across the temporal urbanization process, offering actionable insights for urban planning (such as urban regeneration and renovation) and stage-targeted public health policies aimed at mitigating potential microbiome-related health risks in an increasingly urbanizing world.