(473f) Biogenic Bubbles Enable Long-Range Microbial Dispersal

Microbial communities usually inhabit confining 3D environments, such as soils and sediments, foods, and gels and tissues in the body. While some microbes can disperse in their surroundings using motility, many are non-motile and can only grow and proliferate locally. Here, we show that even non-motile microbes can escape their local microenvironments and achieve long-range dispersal by riding bubbles generated through metabolic activity. Using transparent 3D granular hydrogel matrices, we simultaneously probe the physiology and mechanics of non-motile yeast colonies under confinement. We show that through fermentation, yeast produce carbon dioxide (CO₂), which initially dissolves into the medium. As fermentation continues, the medium reaches supersaturation, triggering the nucleation of CO₂ bubbles. These biogenic bubbles grow, deform the surrounding matrix, and rise—entraining yeast cells over large vertical distances. The motion of the bubbles leaves behind a lasting imprint in the matrix, creating preferential paths that serve as nucleation sites for subsequent bubbles. This sequential entrainment process culminates in the formation of a stable conduit that encapsulates the colony and gives rise to a distinct columnar morphology. Simulations of bubble dynamics in a viscoplastic medium underscore the critical role of sequential entrainment in shaping the columnar structure. Together, our findings provide quantitative insight into biogenic bubble-driven entrainment as a mechanism for microbial dispersal in confined environments. They reveal how microbial metabolism can directly influence the mechanics of the surrounding medium, enabling transport and proliferation in the absence of motility—mirroring biogeophysical processes observed in nature.