Cooperation, Cheating, and Robustness in Cyanobacteria Colonies
Sean Shaheen
Department of Physics and Astronomy, Denver University
Date and time:
Thursday, April 14, 2011 - 4:30pm
Abstract:
Cyanobacteria are the oldest photosynthetic organisms on earth and have shaped much of our environment and ecology. Their colonies exhibit a rich array of dynamics stemming from a division of labor between vegetative cells that undergo photosynthesis and terminally-differentiated heterocyst cells that undergo nitrogen fixation. These different types of cells behave cooperatively by exchanging compounds in order to increase the robustness of the colony under environmental duress. In addition, there is a “cheater” type of cell that behaves like a vegetative cell but produces heterocyst offspring at a reduced rate, thus gaining an evolutionary advantage. My group has begun studies of cyanobacteria guided by the increasing interest in harnessing their metabolism for the purpose of biofuel synthesis. I will discuss our initial efforts at modeling the growth and dynamics of these colonies using systems of ODEs that capture the populations of the different types of cells and the rate constants for their metabolic processes. The initial, transient dynamics are analyzed along with the steady-state solutions. Additionally, the introduction of stochasticity through implementation of the Gillespie first-reaction method will be discussed.