Morphological Instabilities in a growing Yeast Colony: Experiment and   Theory
  We study the growth of colonies of the yeast Pichia membranaefaciens on agarose film. The growth conditions are controlled in a setup where nutrients are supplied through an agarose film suspended over a solution of nutrients. As the thickness of the agarose film is varied, the morphology of the front of the colony changes. The growth of the front is modeled by coupling it to a diffusive field of inhibitory metabolites. Qualitative agreement with experiments suggests that such a coupling is responsible for the observed instability of the front. 
Thomas Sams, Kim Sneppen, and Mogens H. Jensen (Niels Bohr Institute,   Denmark), B.E. Christensen (Novo Nordisk), Ulf Thran...