Winogradsky column

Invented in the 1880s by Sergei Winogradsky, the device is a column of pond mud and water mixed with a carbon source such as newspaper (containing cellulose), blackened marshmallows or egg-shells (containing calcium carbonate), and a sulfur source such as gypsum (calcium sulfate) or egg yolk.

These two gradients promote the growth of different microorganisms such as Clostridium, Desulfovibrio, Chlorobium, Chromatium, Rhodomicrobium, and Beggiatoa, as well as many other species of bacteria, cyanobacteria, and algae.

Anaerobic phototrophs are still present to a large extent in the mud phase, and there is still capacity for biofilm creation and colony expansion.

Alternatively, some procedures call for sand to be used for the layer above the enriched sediment as to allow for easier observation and sampling of resulting populations.

However its importance in environmental microbiology should not be overlooked and it is still an excellent tool to determine the major bacterial communities in a sample.

This picture depicts the initial appearance of three different Winogradsky columns. They are soil and water samples from a river, the later two columns have been modified with phosphate, nitrate, sulfur and oxygen additives. These additions promote the growth of various bacteria specific to the anaerobic and aerobic regions of the column.
Shown above as a result of a 7-week period where the columns have been allowed to grow algae , cyanobacteria and other bacterial colonies. Of specific interest are the red regions of the middle column, indicative of purple non-sulfur bacteria (e.g. Rhodospirillaceae ). Also, in column three, the red growth along the side of the column: a purple sulfur bacterium, Chromatium .