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Pattern formation and collective behavior in bacterial colonies in stressed environments

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Date and time:Ìý

Thursday, April 23, 2015 - 2:00pm

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ECCR 257

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Bacterial colonies are capable of highly sophisticated collective behavior in order to adapt to environmental stresses and increase the likelihood of their survival. This can result in the formation of complex spatial patterns patterns, stunning examples of which can be seen in colonies of Paenabacillis dentritiformis. When grown under nutrient-poor conditions this bacterium can form dendritic patterns that exhibit rich statistical properties and fractal structure, the details of which depend on the concentration and type of nutrients.

Here I present our work on analyzing the fractal dimension of P. dentritiformis grown under various environments, through graphical analysis of microscopy images. We find that fractal structure can emerge by growing the colonies on either low concentrations of a good nutrient or high concentrations of a poor nutrient, each resulting
in different types of spatial structures. We also find that fractal structure is retained when P. dentritiformis is grown together in a co-colony with another non-fractal forming bacterium.Ìý I will conclude by discussing initial attempts at modeling the dynamics of intercellular communication in such systems, in which the physical geometry of the colony determines the connectivity map of the cells and hence strongly dictates the overall colony behavior.