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I've never heard of it

Laboratory experiment named after pioneer microbiologist Sergius Winogradsky (1856-1953), who was studying the metabolic processes of prokaryotic bacteria and archaea. He and Martinus Willem Beijerinck (1851-1931) determined that bacteria are metabolically more diverse than "more complex" lifeforms, and that they make the world go round by doing almost all of the nutrient cycling on the planet.

At the time, other pioneer microbiologists like Louis Pasteur and Robert Koch were studying microbes in what is referred to as pure culture studies. Winogradsky studied microbial inter-relationships in mixed communities.

Winogradsky came up with an easy way to study this. The Winogradsky Column was born. The column can be used to show how different microbes perform their interdependent roles in a completely self contained system of recycling. Note: needs sunlight.

The column is made in a glass/perspex tube. A small practical size is 30cm long, 5cm wide (12in x 2in), although some people have made huge ones. Mud from the bottom of a river or lake goes at the bottom. This mud is supplemented with cellulose (e.g. newspaper), sodium sulphate and calcium carbonate. The rest of the column is filled with water from a river or lake. then the lid is put on and put it near the window. It will sit in the window for a few months and incubate.

Eventually, you will start to see some patterns emerging. there should be some distinct layers forming. The principle is that the microbes will proliferate and then settle into their niche in the column. The general idea is that the cellulose will initially promote rapid growth, and quickly exhaust all the O2 in the column. Aerobic microbes will only survive at the top, because of O2's slow diffusion rate in water. Microorganisms capable of fermentation will survive deeper in the column, as will those capable of anaerobic respiration. The anaerobic sediment at the bottom of the column will most likely be populated by Clostridium and Desulfovibrio species. Above the sediment, inverse gradients of H2S and SO4 will appear with the formation of the anaerobic photosynthates, green sulphur and purple sulphur bacteria layers. Above this will be anaerobic water, with purple non sulphur bacteria. Above this will be the aerobic water. This will be dominated by cyanobacteria and sulphur oxidising bacteria. Above these will be 'sheathed bacteria', microbes that build filamentous sheaths of protein, lipids and polysaccharides. This is hypothesised to be a predation defense.

A word of warning. Whilst these are interesting and very easy to build, I would not recommend you do this. Why? Because they aren't very attractive, take a long time to grow, and can smell bad from the sulphur and iron metabolism. It's a lot like composting, just with more water. Would you compost in your own home?

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