Biogenic bubbles enable long-range microbial dispersal

Microbial communities are key architects of ecosystems, shaping global biogeochemical cycles by colonizing physically confined, yield-stress environments such as soils and sediments. In these settings, strong physical constraints suppress the two canonical mechanisms of microbial range expansion—motility and growth—leaving the dispersal strategies of immotile populations poorly understood.

Here, we use transparent granular hydrogel matrices as a model yield-stress environment to show that confined yeast populations can achieve long-range dispersal by harnessing metabolism to generate motion. Under anaerobic conditions, fermentation drives the accumulation of dissolved CO₂, which gradually reaches supersaturation and nucleates gas bubbles. These biogenic bubbles grow, deform the matrix, and ascend slowly, entraining cells in their wake. Repeated nucleation along the same path sculpts a persistent conduit, giving rise to striking columnar colony morphologies.

By revisiting Darwin’s drift mechanism, we quantify hydrodynamic entrainment in a viscoplastic medium and demonstrate that sequential bubble nucleation and rise are essential for column formation. Our findings uncover a metabolically driven mode of microbial dispersal, offering new insights into how microorganisms invade and reshape confined environments—processes with direct relevance to soil ecology, sedimentary gas release, and subsurface biophysics.