EARLY DEVELOPMENTAL PROGRAM SHAPES COLONY MORPHOLOGY IN BACTERIA

When grown on a solid surface, bacteria form highly organized colonies, yet little is known about the earliest stages of colony establishment. Following Bacillus subtilis colony development from a single progenitor cell, revealed a sequence of highly ordered spatio-temporal events. Colony was initiated by the formation of leading cell chains, deriving from the colony center and extending in multiple directions, typically in a "Y shape" structure. By eradicating particular cells during these early stages, we could influence the shape of the resulting colony and demonstrate that "Y arm" extension defines colony size. A mutant in ymdB, encoding a phosphodiesterase, displayed unordered developmental patterns, indicating a role in guiding these initial events. Finally, we provide evidence that intercellular nanotubes contribute to proper colony formation. Collectively, we revealed the existence of a "construction plan" for building a colony, and provide the initial molecular basis for this process.