Sergei N. Winogradsky was one of the first microbiologists to study the organisms found in complex biofilm communities. One of the strategies he used to isolate organisms from nature was a miniature model of a pond cross-section that is now called a Winogradsky column. It is a simple device for constructing a stratified ecosystem and provides a visual example of various modes of metabolism and zonation in the microbial world. It is a classic demonstration of the metabolic diversity of prokaryotes. The poster shows the different bacteria found in each zone, their metabolic niches, and the gradients of energy sources.