Abstract

Microorganisms inhabit highly fluctuating natural environments and survive in a low-nutrient resource baths. It is now well recognized that nutrient exchanges among microbes play a vital role in their survival. The existence of such exchanges raises fundamental questions about the dynamics of these interactions. In this talk, we will explore experimentally and theoretically a realization of such interactions in which active bacteria dynamically respond to the oxygen produced by immotile green algae through photosynthesis. Even in this simplest mixture of active-passive suspensions, we find a complex dynamics involving nutrient exchanges and enhanced algal diffusivity due to the bacteria. Towards the end of the talk, I will briefly discuss our investigations on collective behaviour in an active fluidic network of filamentous fungi, which presents another fascinating example of dynamical complexity in living systems.