Hub taxa are keystone microbes during early succession

Microorganisms underpin numerous ecosystem processes and support biodiversity globally, yet we understand surprisingly little about what structures environmental microbiomes themselves. Combining culturing, sequencing, and microbial networks, we identified ‘central’ (highly-connected, hub taxa), ‘intermediate’ (moderately-connected), and ‘peripheral’ (weakly/un-connected) microbes and experimentally evaluated their effects on soil microbiome assembly during early succession. Our results demonstrate central early colonizers significantly (1) enhanced biodiversity, (2) increased recruitment of additional influential, hub taxa, and (3) shaped microbiome assembly trajectories. This work elucidates fundamental principles of network theory in microbial ecology and demonstrates for the first time in nature that central, hub microbes are keystones.