The interaction of thin-film flow, bacterial swarming and cell differentiation in colonies of Serratia liquefaciens

The rate of expansion of bacterial colonies of S. liquefaciens is investiga ted in terms of a mathematical model that combines biological as well as hy drodynamic processes. The relative importance of cell differentiation and p roduction of an extracellular wetting agent to bacterial swarming is explor ed using a continuum representation. The model incorporates aspects of thin film flow with variable suspension viscosity, wetting, and cell differenti ation. Experimental evidence suggests that the bacterial colony is highly s ensitive to its environment and that a variety of mechanisms are exploited in order to proliferate on a variety of surfaces. It is found that a combin ation of effects are required to reproduce the variation of bacterial colon y motility over a large range of nutrient availability and medium hardness.